Fix warnings.

Conflicts:
	src/libserver/spf.c
	src/libstat/backends/mmaped_file.c
	src/libutil/expression.c

src/lua/lua_task.c

@@ -1239,7 +1239,7 @@ lua_task_get_queue_id (lua_State *L)
 {
 	struct rspamd_task *task = lua_check_task (L, 1);
 
-	if (task && task->queue_id != NULL && task->queue_id != "undef") {
+	if (task && task->queue_id != NULL && strcmp (task->queue_id, "undef") != 0) {
 		lua_pushstring (L, task->queue_id);
 		return 1;
 	}