Don't destroy confbridge config when error is encountered during a reload.

Not panicking means that the old config is kept.

(closes issue ASTERISK-20458)
Reported by: Leif Madsen
Patches:
	ASTERISK-20458.patch uploaded by Mark Michelson(license #5049)
Tested by Leif Madsen
........

Merged revisions 374106 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@374107 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/confbridge/conf_config_parser.c

@@ -1316,7 +1316,10 @@ int conf_load_config(int reload)
 
 	return 0;
 error:
-	conf_destroy_config();
+	/* On a reload, just keep the config we already have in place. */
+	if (!reload) {
+		conf_destroy_config();
+	}
 	return -1;
 }