zalloc the libinput_source, don't malloc it

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>

src/libinput.c

@@ -510,7 +510,7 @@ libinput_add_fd(struct libinput *libinput,
 	struct libinput_source *source;
 	struct epoll_event ep;
 
-	source = malloc(sizeof *source);
+	source = zalloc(sizeof *source);
 	if (!source)
 		return NULL;