https://github.com/nm-l2tp/NetworkManager-l2tp/pull/208

From bf46aec299c58321703f5431ebafcce561a98cef Mon Sep 17 00:00:00 2001
From: Sam James <sam@gentoo.org>
Date: Sun, 23 Apr 2023 09:16:24 +0100
Subject: [PATCH] configure.ac: fix bashisms in configure.ac

configure scripts need to be runnable with a POSIX-compliant /bin/sh.

On many (but not all!) systems, /bin/sh is provided by Bash, so errors
like this aren't spotted. Notably Debian defaults to /bin/sh provided
by dash which doesn't tolerate such bashisms as '=='.

This retains compatibility with bash.
--- a/configure.ac
+++ b/configure.ac
@@ -197,7 +197,7 @@ fi
 AM_CONDITIONAL(WITH_GNOME, test "$with_gnome" != no)
 
 AC_ARG_WITH(gtk4, AS_HELP_STRING([--with-gtk4], [Build NetworkManager-l2tp with libnma-gtk4 support]), [], [with_gtk4_specified=no])
-if test "$with_gtk4_specified" == no; then
+if test "$with_gtk4_specified" = no; then
 	with_gtk4=no
 fi
 if test "$with_gtk4" != yes; then
@@ -256,7 +256,7 @@ NM_LD_GC
 
 NM_PLUGIN_DIR="$libdir/NetworkManager"
 AC_SUBST(NM_PLUGIN_DIR)
-if test x"$enable_absolute_paths" == x"yes"; then
+if test x"$enable_absolute_paths" = x"yes"; then
 	NM_PLUGIN_DIR_NAME_FILE="$NM_PLUGIN_DIR/"
 else
 	enable_absolute_paths=no