quartz: Fix call to missing symbol
quartz: Fix call to missing symbol

This patch can be considered a leftover of commit a269c2f8d26a ,
replace the no longer existing function with the GDK function
meant to replace it.

This was noticeable on regular clipboard operations in quartz

Distrotech/gtk,Distrotech/gtk,johne53/MB3Gtk-2,johne53/MB3Gtk-2,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,Distrotech/gtk