s3:mdssvc: older glib2 versions require g_type_init()

s3:mdssvc: older glib2 versions require g_type_init()

Older glib2 versions will crash if g_type_init is not called:

(process:6712): GLib-GObject-CRITICAL **: ... ./gobject/gtype.c:2722:
You forgot to call g_type_init()

Bug: https://bugzilla.samba.org/show_bug.cgi?id=11801

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Mar 18 03:52:55 CET 2016 on sn-devel-144

(cherry picked from commit 3563d79a8cb625ae78523cb32330c9f61c6c3a2f)