configure*: Add missing quotes to arguments

For increased safety and consistency.  In addition, this should make it
clearer where each argument starts and ends.

See also the following item from autoconf NEWS[1]:

> * Noteworthy changes in release 2.70 (2020-12-08) [stable]

[...]

> *** Many macros have become pickier about argument quotation.
>
>   If you get a shell syntax error from your generated configure
>   script, or seemingly impossible misbehavior (e.g. entire blocks of
>   the configure script not getting executed), check first that all
>   macro arguments are properly quoted. The “M4 Quotation” section of
>   the manual explains how to quote macro arguments properly.
>
>   It is unfortunately not possible for autoupdate to correct
>   quotation errors.

[1] https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=blob;f=NEWS;h=ba418d1af5da752de77a2c388f9af56f8f1bf6a4;hb=97fbc5c184acc6fa591ad094eae86917f03459fa

configure

@@ -3562,10 +3562,10 @@ HAVE_OVERLAYFS=""
 
 #
 #AC_ARG_ENABLE([overlayfs],
-#    AS_HELP_STRING([--disable-overlayfs], [disable overlayfs]))
+#    [AS_HELP_STRING([--disable-overlayfs], [disable overlayfs])])
 #AS_IF([test "x$enable_overlayfs" != "xno"], [
 #	HAVE_OVERLAYFS="-DHAVE_OVERLAYFS"
-#	AC_SUBST(HAVE_OVERLAYFS)
+#	AC_SUBST([HAVE_OVERLAYFS])
 #])
 
 HAVE_OUTPUT=""

configure.ac

@@ -41,13 +41,14 @@ AX_CHECK_COMPILE_FLAG(
 )
 
 AC_ARG_ENABLE([analyzer],
-    AS_HELP_STRING([--enable-analyzer], [enable GCC static analyzer]))
+    [AS_HELP_STRING([--enable-analyzer], [enable GCC static analyzer])])
 AS_IF([test "x$enable_analyzer" = "xyes"], [
 	EXTRA_CFLAGS="$EXTRA_CFLAGS -fanalyzer -Wno-analyzer-malloc-leak"
 ])
 
 AC_ARG_ENABLE([sanitizer],
-    AS_HELP_STRING([--enable-sanitizer=@<:@address | memory | undefined@:>@], [enable a compiler-based sanitizer (debug)]), [], [enable_sanitizer=no])
+    [AS_HELP_STRING([--enable-sanitizer=@<:@address | memory | undefined@:>@], [enable a compiler-based sanitizer (debug)])],
+    [], [enable_sanitizer=no])
 AS_IF([test "x$enable_sanitizer" != "xno" ],
 	[AX_CHECK_COMPILE_FLAG([-fsanitize=$enable_sanitizer], [
 		EXTRA_CFLAGS="$EXTRA_CFLAGS -fsanitize=$enable_sanitizer -fno-omit-frame-pointer"
@@ -57,21 +58,21 @@ AS_IF([test "x$enable_sanitizer" != "xno" ],
 
 HAVE_APPARMOR=""
 AC_ARG_ENABLE([apparmor],
-    AS_HELP_STRING([--enable-apparmor], [enable apparmor]))
+    [AS_HELP_STRING([--enable-apparmor], [enable apparmor])])
 AS_IF([test "x$enable_apparmor" = "xyes"], [
 	HAVE_APPARMOR="-DHAVE_APPARMOR"
-	PKG_CHECK_MODULES([AA], libapparmor,
+	PKG_CHECK_MODULES([AA], [libapparmor],
 	    [EXTRA_CFLAGS="$EXTRA_CFLAGS $AA_CFLAGS" && EXTRA_LDFLAGS="$EXTRA_LDFLAGS $AA_LIBS"])
-	AC_SUBST(HAVE_APPARMOR)
+	AC_SUBST([HAVE_APPARMOR])
 ])
 
 HAVE_SELINUX=""
 AC_ARG_ENABLE([selinux],
-    AS_HELP_STRING([--enable-selinux], [SELinux labeling support]))
+    [AS_HELP_STRING([--enable-selinux], [SELinux labeling support])])
 AS_IF([test "x$enable_selinux" = "xyes"], [
 	HAVE_SELINUX="-DHAVE_SELINUX"
 	EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lselinux"
-	AC_SUBST(HAVE_SELINUX)
+	AC_SUBST([HAVE_SELINUX])
 ])
 
 AC_SUBST([EXTRA_CFLAGS])
@@ -80,219 +81,220 @@ AC_SUBST([EXTRA_LDFLAGS])
 
 HAVE_DBUSPROXY=""
 AC_ARG_ENABLE([dbusproxy],
-    AS_HELP_STRING([--disable-dbusproxy], [disable dbus proxy]))
+    [AS_HELP_STRING([--disable-dbusproxy], [disable dbus proxy])])
 AS_IF([test "x$enable_dbusproxy" != "xno"], [
 	HAVE_DBUSPROXY="-DHAVE_DBUSPROXY"
-	AC_SUBST(HAVE_DBUSPROXY)
+	AC_SUBST([HAVE_DBUSPROXY])
 ])
 
 # overlayfs features temporarily disabled pending fixes
 HAVE_OVERLAYFS=""
-AC_SUBST(HAVE_OVERLAYFS)
+AC_SUBST([HAVE_OVERLAYFS])
 #
 #AC_ARG_ENABLE([overlayfs],
-#    AS_HELP_STRING([--disable-overlayfs], [disable overlayfs]))
+#    [AS_HELP_STRING([--disable-overlayfs], [disable overlayfs])])
 #AS_IF([test "x$enable_overlayfs" != "xno"], [
 #	HAVE_OVERLAYFS="-DHAVE_OVERLAYFS"
-#	AC_SUBST(HAVE_OVERLAYFS)
+#	AC_SUBST([HAVE_OVERLAYFS])
 #])
 
 HAVE_OUTPUT=""
 AC_ARG_ENABLE([output],
-    AS_HELP_STRING([--disable-output], [disable --output logging]))
+    [AS_HELP_STRING([--disable-output], [disable --output logging])])
 AS_IF([test "x$enable_output" != "xno"], [
 	HAVE_OUTPUT="-DHAVE_OUTPUT"
-	AC_SUBST(HAVE_OUTPUT)
+	AC_SUBST([HAVE_OUTPUT])
 ])
 
 HAVE_USERTMPFS=""
 AC_ARG_ENABLE([usertmpfs],
-    AS_HELP_STRING([--disable-usertmpfs], [disable tmpfs as regular user]))
+    [AS_HELP_STRING([--disable-usertmpfs], [disable tmpfs as regular user])])
 AS_IF([test "x$enable_usertmpfs" != "xno"], [
 	HAVE_USERTMPFS="-DHAVE_USERTMPFS"
-	AC_SUBST(HAVE_USERTMPFS)
+	AC_SUBST([HAVE_USERTMPFS])
 ])
 
 HAVE_MAN="no"
 AC_ARG_ENABLE([man],
-    AS_HELP_STRING([--disable-man], [disable man pages]))
+    [AS_HELP_STRING([--disable-man], [disable man pages])])
 AS_IF([test "x$enable_man" != "xno"], [
 	HAVE_MAN="-DHAVE_MAN"
-	AC_SUBST(HAVE_MAN)
+	AC_SUBST([HAVE_MAN])
 	AC_CHECK_PROG([HAVE_GAWK], [gawk], [yes], [no])
 	AS_IF([test "x$HAVE_GAWK" != "xyes"], [AC_MSG_ERROR([*** gawk not found ***])])
 ])
 
 HAVE_FIRETUNNEL=""
 AC_ARG_ENABLE([firetunnel],
-    AS_HELP_STRING([--disable-firetunnel], [disable firetunnel]))
+    [AS_HELP_STRING([--disable-firetunnel], [disable firetunnel])])
 AS_IF([test "x$enable_firetunnel" != "xno"], [
 	HAVE_FIRETUNNEL="-DHAVE_FIRETUNNEL"
-	AC_SUBST(HAVE_FIRETUNNEL)
+	AC_SUBST([HAVE_FIRETUNNEL])
 ])
 
 HAVE_PRIVATEHOME=""
 AC_ARG_ENABLE([private-home],
-    AS_HELP_STRING([--disable-private-home], [disable private home feature]))
+    [AS_HELP_STRING([--disable-private-home], [disable private home feature])])
 AS_IF([test "x$enable_private_home" != "xno"], [
 	HAVE_PRIVATE_HOME="-DHAVE_PRIVATE_HOME"
-	AC_SUBST(HAVE_PRIVATE_HOME)
+	AC_SUBST([HAVE_PRIVATE_HOME])
 ])
 
 HAVE_CHROOT=""
 AC_ARG_ENABLE([chroot],
-    AS_HELP_STRING([--disable-chroot], [disable chroot]))
+    [AS_HELP_STRING([--disable-chroot], [disable chroot])])
 AS_IF([test "x$enable_chroot" != "xno"], [
 	HAVE_CHROOT="-DHAVE_CHROOT"
-	AC_SUBST(HAVE_CHROOT)
+	AC_SUBST([HAVE_CHROOT])
 ])
 
 HAVE_GLOBALCFG=""
 AC_ARG_ENABLE([globalcfg],
-    AS_HELP_STRING([--disable-globalcfg], [if the global config file firejail.cfg is not present, continue the program using defaults]))
+    [AS_HELP_STRING([--disable-globalcfg],
+        [if the global config file firejail.cfg is not present, continue the program using defaults])])
 AS_IF([test "x$enable_globalcfg" != "xno"], [
 	HAVE_GLOBALCFG="-DHAVE_GLOBALCFG"
-	AC_SUBST(HAVE_GLOBALCFG)
+	AC_SUBST([HAVE_GLOBALCFG])
 ])
 
 HAVE_NETWORK=""
 AC_ARG_ENABLE([network],
-    AS_HELP_STRING([--disable-network], [disable network]))
+    [AS_HELP_STRING([--disable-network], [disable network])])
 AS_IF([test "x$enable_network" != "xno"], [
 	HAVE_NETWORK="-DHAVE_NETWORK"
-	AC_SUBST(HAVE_NETWORK)
+	AC_SUBST([HAVE_NETWORK])
 ])
 
 HAVE_USERNS=""
 AC_ARG_ENABLE([userns],
-    AS_HELP_STRING([--disable-userns], [disable user namespace]))
+    [AS_HELP_STRING([--disable-userns], [disable user namespace])])
 AS_IF([test "x$enable_userns" != "xno"], [
 	HAVE_USERNS="-DHAVE_USERNS"
-	AC_SUBST(HAVE_USERNS)
+	AC_SUBST([HAVE_USERNS])
 ])
 
 HAVE_X11=""
 AC_ARG_ENABLE([x11],
-    AS_HELP_STRING([--disable-x11], [disable X11 sandboxing support]))
+    [AS_HELP_STRING([--disable-x11], [disable X11 sandboxing support])])
 AS_IF([test "x$enable_x11" != "xno"], [
 	HAVE_X11="-DHAVE_X11"
-	AC_SUBST(HAVE_X11)
+	AC_SUBST([HAVE_X11])
 ])
 
 HAVE_FILE_TRANSFER=""
 AC_ARG_ENABLE([file-transfer],
-    AS_HELP_STRING([--disable-file-transfer], [disable file transfer]))
+    [AS_HELP_STRING([--disable-file-transfer], [disable file transfer])])
 AS_IF([test "x$enable_file_transfer" != "xno"], [
 	HAVE_FILE_TRANSFER="-DHAVE_FILE_TRANSFER"
-	AC_SUBST(HAVE_FILE_TRANSFER)
+	AC_SUBST([HAVE_FILE_TRANSFER])
 ])
 
 HAVE_SUID=""
 AC_ARG_ENABLE([suid],
-    AS_HELP_STRING([--disable-suid], [install as a non-SUID executable]))
+    [AS_HELP_STRING([--disable-suid], [install as a non-SUID executable])])
 AS_IF([test "x$enable_suid" = "xno"],
 	[HAVE_SUID="no"],
 	[HAVE_SUID="yes"]
 )
-AC_SUBST(HAVE_SUID)
+AC_SUBST([HAVE_SUID])
 
 HAVE_FATAL_WARNINGS=""
 AC_ARG_ENABLE([fatal_warnings],
-    AS_HELP_STRING([--enable-fatal-warnings], [-W -Wall -Werror]))
+    [AS_HELP_STRING([--enable-fatal-warnings], [-W -Wall -Werror])])
 AS_IF([test "x$enable_fatal_warnings" = "xyes"], [
 	HAVE_FATAL_WARNINGS="-W -Wall -Werror"
-	AC_SUBST(HAVE_FATAL_WARNINGS)
+	AC_SUBST([HAVE_FATAL_WARNINGS])
 ])
 
 BUSYBOX_WORKAROUND="no"
 AC_ARG_ENABLE([busybox-workaround],
-    AS_HELP_STRING([--enable-busybox-workaround], [enable busybox workaround]))
+    [AS_HELP_STRING([--enable-busybox-workaround], [enable busybox workaround])])
 AS_IF([test "x$enable_busybox_workaround" = "xyes"], [
 	BUSYBOX_WORKAROUND="yes"
-	AC_SUBST(BUSYBOX_WORKAROUND)
+	AC_SUBST([BUSYBOX_WORKAROUND])
 ])
 
 
 HAVE_GCOV=""
 AC_ARG_ENABLE([gcov],
-    AS_HELP_STRING([--enable-gcov], [Gcov instrumentation]))
+    [AS_HELP_STRING([--enable-gcov], [Gcov instrumentation])])
 AS_IF([test "x$enable_gcov" = "xyes"], [
 	HAVE_GCOV="--coverage -DHAVE_GCOV"
 	EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lgcov --coverage"
-	AC_SUBST(HAVE_GCOV)
+	AC_SUBST([HAVE_GCOV])
 ])
 
 HAVE_CONTRIB_INSTALL="yes"
 AC_ARG_ENABLE([contrib-install],
-    AS_HELP_STRING([--enable-contrib-install], [install contrib scripts]))
+    [AS_HELP_STRING([--enable-contrib-install], [install contrib scripts])])
 AS_IF([test "x$enable_contrib_install" = "xno"],
 	[HAVE_CONTRIB_INSTALL="no"],
 	[HAVE_CONTRIB_INSTALL="yes"]
 )
-AC_SUBST(HAVE_CONTRIB_INSTALL)
+AC_SUBST([HAVE_CONTRIB_INSTALL])
 
 HAVE_FORCE_NONEWPRIVS=""
 AC_ARG_ENABLE([force-nonewprivs],
-    AS_HELP_STRING([--enable-force-nonewprivs], [enable force nonewprivs]))
+    [AS_HELP_STRING([--enable-force-nonewprivs], [enable force nonewprivs])])
 AS_IF([test "x$enable_force_nonewprivs" = "xyes"], [
 	HAVE_FORCE_NONEWPRIVS="-DHAVE_FORCE_NONEWPRIVS"
-	AC_SUBST(HAVE_FORCE_NONEWPRIVS)
+	AC_SUBST([HAVE_FORCE_NONEWPRIVS])
 ])
 
 HAVE_LTS=""
 AC_ARG_ENABLE([lts],
-    AS_HELP_STRING([--enable-lts], [enable long-term support software version (LTS)]))
+    [AS_HELP_STRING([--enable-lts], [enable long-term support software version (LTS)])])
 AS_IF([test "x$enable_lts" = "xyes"], [
 	HAVE_LTS="-DHAVE_LTS"
-	AC_SUBST(HAVE_LTS)
+	AC_SUBST([HAVE_LTS])
 
 	HAVE_DBUSPROXY=""
-	AC_SUBST(HAVE_DBUSPROXY)
+	AC_SUBST([HAVE_DBUSPROXY])
 
 	HAVE_OVERLAYFS=""
-	AC_SUBST(HAVE_OVERLAYFS)
+	AC_SUBST([HAVE_OVERLAYFS])
 
 	HAVE_OUTPUT=""
-	AC_SUBST(HAVE_OUTPUT)
+	AC_SUBST([HAVE_OUTPUT])
 
 	HAVE_USERTMPFS=""
-	AC_SUBST(HAVE_USERTMPFS)
+	AC_SUBST([HAVE_USERTMPFS])
 
 	HAVE_MAN="-DHAVE_MAN"
-	AC_SUBST(HAVE_MAN)
+	AC_SUBST([HAVE_MAN])
 
 	HAVE_FIRETUNNEL=""
-	AC_SUBST(HAVE_FIRETUNNEL)
+	AC_SUBST([HAVE_FIRETUNNEL])
 
 	HAVE_PRIVATEHOME=""
-	AC_SUBST(HAVE_PRIVATE_HOME)
+	AC_SUBST([HAVE_PRIVATE_HOME])
 
 	HAVE_CHROOT=""
-	AC_SUBST(HAVE_CHROOT)
+	AC_SUBST([HAVE_CHROOT])
 
 	HAVE_GLOBALCFG=""
-	AC_SUBST(HAVE_GLOBALCFG)
+	AC_SUBST([HAVE_GLOBALCFG])
 
 	HAVE_USERNS=""
-	AC_SUBST(HAVE_USERNS)
+	AC_SUBST([HAVE_USERNS])
 
 	HAVE_X11=""
-	AC_SUBST(HAVE_X11)
+	AC_SUBST([HAVE_X11])
 
 	HAVE_FILE_TRANSFER=""
-	AC_SUBST(HAVE_FILE_TRANSFER)
+	AC_SUBST([HAVE_FILE_TRANSFER])
 
 	HAVE_SUID="yes"
-	AC_SUBST(HAVE_SUID)
+	AC_SUBST([HAVE_SUID])
 
 	BUSYBOX_WORKAROUND="no"
-	AC_SUBST(BUSYBOX_WORKAROUND)
+	AC_SUBST([BUSYBOX_WORKAROUND])
 
 	HAVE_CONTRIB_INSTALL="no",
-	AC_SUBST(HAVE_CONTRIB_INSTALL)
+	AC_SUBST([HAVE_CONTRIB_INSTALL])
 ])
 
-AC_CHECK_HEADER([linux/seccomp.h],,AC_MSG_ERROR([*** SECCOMP support is not installed (/usr/include/linux/seccomp.h missing) ***]))
+AC_CHECK_HEADER([linux/seccomp.h], [], AC_MSG_ERROR([*** SECCOMP support is not installed (/usr/include/linux/seccomp.h missing) ***]))
 
 # set sysconfdir
 if test "$prefix" = /usr; then