signal: return TRUE from g_signal_has_handler_pending for custom class closure
signal: return TRUE from g_signal_has_handler_pending for custom class closure

This is almost always what you want, because if you're using this you
want to know if any "custom code" (i.e. not the default class closure)
is going to be run if you emit this signal.

I looked at all the existing uses of this and they were all broken in the
presence of g_signal_override_class_closure().

https://bugzilla.gnome.org/show_bug.cgi?id=754986

endlessm/glib,johne53/MB3Glib,mzabaluev/glib,cention-sany/glib,ieei/glib,cention-sany/glib,endlessm/glib,ieei/glib,tchakabam/glib,Distrotech/glib,ieei/glib,MathieuDuponchelle/glib,endlessm/glib,tchakabam/glib,mzabaluev/glib,mzabaluev/glib,cention-sany/glib,mzabaluev/glib,endlessm/glib,MathieuDuponchelle/glib,Distrotech/glib,Distrotech/glib,johne53/MB3Glib,tchakabam/glib,MathieuDuponchelle/glib,endlessm/glib,ieei/glib,MathieuDuponchelle/glib,tchakabam/glib,Distrotech/glib,ieei/glib,MathieuDuponchelle/glib,johne53/MB3Glib,cention-sany/glib,tchakabam/glib,johne53/MB3Glib,Distrotech/glib,mzabaluev/glib,johne53/MB3Glib,johne53/MB3Glib,cention-sany/glib