gdbus: Fix atomic accesses to global name watch ID
gdbus: Fix atomic accesses to global name watch ID

https://bugzilla.gnome.org/show_bug.cgi?id=777307

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib