Fix memory leak when failing to read config file

In the case of error during my_load_defaults, we would not free the
args array.

mysys/default.c

@@ -577,6 +577,7 @@ int my_load_defaults(const char *conf_file, const char **groups,
                                      handle_default_option, (void *) &ctx,
                                      dirs)))
   {
+    delete_dynamic(&args);
     free_root(&alloc,MYF(0));
     DBUG_RETURN(error);
   }