Removing support for storage engines being loadable, will push featureto 5.2.

sql/sql_plugin.cc:
  Removed support for Storage gneines.

sql/sql_plugin.cc

@@ -517,15 +517,8 @@ static int plugin_initialize(struct st_plugin_int *plugin)
   switch (plugin->plugin->type)
   {
   case MYSQL_STORAGE_ENGINE_PLUGIN:
-    if (ha_initialize_handlerton((handlerton*) plugin->plugin->info))
-    {
-      sql_print_error("Plugin '%s' handlerton init returned error.",
-                      plugin->name.str);
-      DBUG_PRINT("warning", ("Plugin '%s' handlerton init returned error.",
-                             plugin->name.str))
-      goto err;
-    }
-    break;
+    sql_print_error("Storage Engine plugins are unsupported in this version.");
+    goto err;
   default:
     break;
   }