fix mem leak from not destrying config (issue #5048)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6432 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_voicemail.c

@@ -6134,6 +6134,7 @@ static int load_config(void)
 			}
 		}
 		ast_mutex_unlock(&vmlock);
+		ast_config_destroy(cfg);
 		return 0;
 	} else {
 		ast_mutex_unlock(&vmlock);