[mutter] plugin: Add META_DECLARE_PLUGIN_WITH_CODE() variant

[Florian Müllner <fmuellner src gnome org>]

commit ec451b46748745a38db3e607b1d7aad4eae481c3
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Jul 23 20:29:02 2018 +0200

    plugin: Add META_DECLARE_PLUGIN_WITH_CODE() variant
    
    Thanks to G_DEFINE_DYNAMIC_TYPE_EXTENDED(), this is a trivial addition that
    will allow using G_IMPLEMENT_INTERFACE_DYNAMIC() or G_ADD_PRIVATE_DYNAMIC()
    when declaring a plugin.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/176

 src/meta/meta-plugin.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/src/meta/meta-plugin.h b/src/meta/meta-plugin.h
index f973ec6ce..3dc428642 100644
--- a/src/meta/meta-plugin.h
+++ b/src/meta/meta-plugin.h
@@ -303,7 +303,7 @@ struct _MetaPluginVersion
 /*
  * Convenience macro to set up the plugin type. Based on GEdit.
  */
-#define META_PLUGIN_DECLARE(ObjectName, object_name)                    \
+#define META_PLUGIN_DECLARE_WITH_CODE(ObjectName, object_name, CODE)    \
   G_MODULE_EXPORT MetaPluginVersion meta_plugin_version =               \
     {                                                                   \
       META_MAJOR_VERSION,                                               \
@@ -312,7 +312,8 @@ struct _MetaPluginVersion
       META_PLUGIN_API_VERSION                                           \
     };                                                                  \
                                                                         \
-  G_DEFINE_DYNAMIC_TYPE(ObjectName, object_name, META_TYPE_PLUGIN)      \
+  G_DEFINE_DYNAMIC_TYPE_EXTENDED(ObjectName, object_name,               \
+                                 META_TYPE_PLUGIN, 0, CODE)             \
                                                                         \
   /* Unused, but required by G_DEFINE_DYNAMIC_TYPE */                   \
   static void                                                           \
@@ -325,6 +326,9 @@ struct _MetaPluginVersion
     return object_name##_get_type ();                                   \
   }                                                                     \
 
+#define META_PLUGIN_DECLARE(ObjectName, object_name)                    \
+  META_PLUGIN_DECLARE_WITH_CODE(ObjectName, object_name, {})
+
 void
 meta_plugin_switch_workspace_completed (MetaPlugin *plugin);