handle allocation error. Found by Klockwork (www.klocwork.com)

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@8469 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_ivr_async.c

@@ -1848,6 +1848,11 @@ SWITCH_DECLARE(switch_status_t) switch_ivr_broadcast(const char *uuid, const cha
 
 	mypath = strdup(path);
 
+	if (!mypath) {
+		switch_core_session_rwunlock(session);
+		return SWITCH_STATUS_MEMERR;
+	}
+
 	if ((nomedia = switch_channel_test_flag(channel, CF_PROXY_MODE))) {
 		switch_ivr_media(uuid, SMF_REBRIDGE);
 	}