unconfigured cdr_custom should not be fatal

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@5316 65c4cc65-6c06-0410-ace0-fbb531ad65f3

cdr/cdr_custom.c

@@ -135,7 +135,7 @@ int load_module(void)
 		if (mf)
 			fclose(mf);
 	}
-	return res;
+	return 0;
 }
 
 int reload(void)