Fix segfault when dialing a typo'd queue

If trying to dial a non-existent queue, there would
be a segfault when attempting to access q->weight, even
though q was NULL. This problem was introduced during
the queue-reset merge and thus only affects trunk.

(closes issue #14643)
Reported by: alecdavis



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@181244 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_queue.c

@@ -1826,11 +1826,13 @@ static struct call_queue *load_realtime_queue(const char *queuename)
 			ast_variables_destroy(queue_vars);
 		}
 		/* update the use_weight value if the queue's has gained or lost a weight */ 
-		if (!q->weight && prev_weight) {
-			ast_atomic_fetchadd_int(&use_weight, -1);
-		}
-		if (q->weight && !prev_weight) {
-			ast_atomic_fetchadd_int(&use_weight, +1);
+		if (q) {
+			if (!q->weight && prev_weight) {
+				ast_atomic_fetchadd_int(&use_weight, -1);
+			}
+			if (q->weight && !prev_weight) {
+				ast_atomic_fetchadd_int(&use_weight, +1);
+			}
 		}
 		/* Other cases will end up with the proper value for use_weight */
 		ao2_unlock(queues);