Drop trailing semi-colon from G_DEFINE_ macro

It's unnecessary, and only adds visual noise; we have been fairly
inconsistent in the past, but the semi-colon-less version clearly
dominates in the code base.

https://bugzilla.gnome.org/show_bug.cgi?id=669355

tests/refcount/properties4.c

@@ -30,7 +30,7 @@ struct _MyBadgerClass
 };
 
 static GType my_badger_get_type (void);
-G_DEFINE_TYPE (MyBadger, my_badger, G_TYPE_OBJECT);
+G_DEFINE_TYPE (MyBadger, my_badger, G_TYPE_OBJECT)
 
 static void my_badger_dispose (GObject * object);