cleanup: plugin unload

* reduce code duplication

sql/sql_plugin.cc

@@ -1263,23 +1263,16 @@ static void plugin_deinitialize(struct st_plugin_int *plugin, bool ref_check)
     remove_status_vars(show_vars);
   }
 
-  if (plugin_type_deinitialize[plugin->plugin->type])
-  {
-    if ((*plugin_type_deinitialize[plugin->plugin->type])(plugin))
+  plugin_type_init deinit= plugin_type_deinitialize[plugin->plugin->type];
+  if (!deinit)
+    deinit= (plugin_type_init)(plugin->plugin->deinit);
+
+  if (deinit && deinit(plugin))
   {
     sql_print_error("Plugin '%s' of type %s failed deinitialization",
                     plugin->name.str, plugin_type_names[plugin->plugin->type].str);
   }
-  }
-  else if (plugin->plugin->deinit)
-  {
-    DBUG_PRINT("info", ("Deinitializing plugin: '%s'", plugin->name.str));
-    if (plugin->plugin->deinit(plugin))
-    {
-      DBUG_PRINT("warning", ("Plugin '%s' deinit function returned error.",
-                             plugin->name.str));
-    }
-  }
+
   plugin->state= PLUGIN_IS_UNINITIALIZED;
 
   if (ref_check && plugin->ref_count)