Fix for bug #54253: memory leak when using I_S plugins w/o deinit method

Free memory allocated by the server for all plugins,
with or without deinit() method.

sql/sql_show.cc

@@ -6930,7 +6930,9 @@ int finalize_schema_table(st_plugin_int *plugin)
   ST_SCHEMA_TABLE *schema_table= (ST_SCHEMA_TABLE *)plugin->data;
   DBUG_ENTER("finalize_schema_table");
 
-  if (schema_table && plugin->plugin->deinit)
+  if (schema_table)
+  {
+    if (plugin->plugin->deinit)
     {
       DBUG_PRINT("info", ("Deinitializing plugin: '%s'", plugin->name.str));
       if (plugin->plugin->deinit(NULL))
@@ -6938,6 +6940,7 @@ int finalize_schema_table(st_plugin_int *plugin)
         DBUG_PRINT("warning", ("Plugin '%s' deinit function returned error.",
                                plugin->name.str));
       }
+    }
     my_free(schema_table, MYF(0));
   }
   DBUG_RETURN(0);