Only dispose of the conference if one was created.

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@55949 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_meetme.c

@@ -2537,8 +2537,10 @@ static int conf_exec(struct ast_channel *chan, void *data)
 					res = conf_run(chan, cnf, confflags.flags, optargs);
 				}
 			}
-			dispose_conf(cnf);
-			cnf = NULL;
+			if (cnf) {
+				dispose_conf(cnf);
+				cnf = NULL;
+			}
 		}
 	} while (allowretry);