handle/make/file: exit 0 if no makefile

There is no reason to err if no Makefile exists.

Just exit with zero status. This makes the following
command work:

./handle make file -c util/*

Within util/, there is me7 update parser which does
not have a makefile (it's a python script).

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/handle/make/file

@@ -44,6 +44,7 @@ handle_dependencies()
 
 run_make_command()
 {
+	[ -f "${project}/Makefile" ] || return 0
 	if [ -z "${mode}" ]; then
 		x_ make -C "${project}" -j$(nproc)
 	else