all: require glib 2.40

RHEL 7.1 and Ubuntu 14.04 LTS both have this.

https://bugzilla.gnome.org/show_bug.cgi?id=792323

examples/C/glib/add-connection-gdbus.c

@@ -124,11 +124,6 @@ main (int argc, char *argv[])
 	GDBusProxy *proxy;
 	GError *error = NULL;
 
-#if !GLIB_CHECK_VERSION (2, 35, 0)
-	/* Initialize GType system */
-	g_type_init ();
-#endif
-
 	/* Create a D-Bus proxy; NM_DBUS_* defined in nm-dbus-interface.h */
 	proxy = g_dbus_proxy_new_for_bus_sync (G_BUS_TYPE_SYSTEM,
 	                                       G_DBUS_PROXY_FLAGS_NONE,