Fix bridging thread leak.

The bridge thread was exiting but was never being
reaped using pthread_join(). This has been fixed now
by calling pthread_join() in ast_bridge_destroy().

(closes issue ASTERISK-19834)
Reported by Marcus Hunger

Review: https://reviewboard.asterisk.org/r/2012
........

Merged revisions 369708 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 369709 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369710 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/bridging.c

@@ -234,9 +234,6 @@ static void bridge_check_dissolve(struct ast_bridge *bridge, struct ast_bridge_c
 		}
 	}
 
-	/* Since all the channels are going away let's go ahead and stop our on thread */
-	bridge->stop = 1;
-
 	return;
 }
 
@@ -544,9 +541,14 @@ int ast_bridge_destroy(struct ast_bridge *bridge)
 		bridge->callid = ast_callid_unref(bridge->callid);
 	}
 
-	bridge->stop = 1;
-
-	bridge_poke(bridge);
+	if (bridge->thread != AST_PTHREADT_NULL) {
+		pthread_t thread = bridge->thread;
+		bridge->stop = 1;
+		bridge_poke(bridge);
+		ao2_unlock(bridge);
+		pthread_join(thread, NULL);
+		ao2_lock(bridge);
+	}
 
 	ast_debug(1, "Telling all channels in bridge %p to end and leave the party\n", bridge);