kbuild: propagate CONFIG_WERROR to resolve_btfids

Use CONFIG_WERROR to also fail on warnings emitted by resolve_btfids.
Allow the CI bots to prevent the introduction of new warnings.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>

scripts/link-vmlinux.sh

@@ -279,7 +279,11 @@ vmlinux_link vmlinux
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then
 	info BTFIDS vmlinux
-	${RESOLVE_BTFIDS} vmlinux
+	RESOLVE_BTFIDS_ARGS=""
+	if is_enabled CONFIG_WERROR; then
+		RESOLVE_BTFIDS_ARGS=" --fatal-warnings "
+	fi
+	${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} vmlinux
 fi
 
 mksysmap vmlinux System.map