[network-manager-applet] build: sync m4/compiler_options.m4 with NetworkManager

[Lubomir Rintel <lkundrak src gnome org>]

commit a0b3cfd604eac8e0a2755c3f40823a5e941257dd
Author: Lubomir Rintel <lkundrak v3 sk>
Date:   Tue Aug 7 17:06:17 2018 +0200

    build: sync m4/compiler_options.m4 with NetworkManager

 m4/compiler_options.m4 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/m4/compiler_options.m4 b/m4/compiler_options.m4
index d42501e8..0683e44e 100644
--- a/m4/compiler_options.m4
+++ b/m4/compiler_options.m4
@@ -58,7 +58,7 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
        dnl attach it to the CFLAGS.
        NM_COMPILER_WARNING([$1], [unknown-warning-option], [])
 
-       CFLAGS="$CFLAGS -Wall"
+       CFLAGS_MORE_WARNINGS="-Wall"
 
        if test "x$set_more_warnings" = xerror; then
                CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror"
@@ -92,7 +92,7 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
                      -Wno-unused-parameter \
                      ; do
                dnl GCC 4.4 does not warn when checking for -Wno-* flags 
(https://gcc.gnu.org/wiki/FAQ#wnowarning)
-               _NM_COMPILER_FLAG([$(printf '%s' "$option" | sed 's/^-Wno-/-W/')], [],
+               _NM_COMPILER_FLAG([-Wall $(printf '%s' "$option" | sed 's/^-Wno-/-W/')], [],
                                  [CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS $option"], [])
        done
        unset option