g_source_set_name on custom sources (if available)

Call g_source_set_name, if the versio of GLib is new enough.
This aids debugging, using e.g. SystemTap.  See
https://bugzilla.gnome.org/show_bug.cgi?id=620511
for more information

http://bugzilla.openedhand.com/show_bug.cgi?id=2151

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>

clutter/clutter-timeout-pool.c

@@ -377,6 +377,10 @@ clutter_timeout_pool_new (gint priority)
   if (!source)
     return NULL;
 
+#if GLIB_CHECK_VERSION (2, 25, 8)
+  g_source_set_name (source, "Clutter timeout pool");
+#endif
+
   if (priority != G_PRIORITY_DEFAULT)
     g_source_set_priority (source, priority);