Make process_all_updates draw synchronously
Make process_all_updates draw synchronously

By calling XSync in _gdk_x11_display_after_process_all_updates we
effectively make gdk rendering sync, which avoids problems with the
client animations running faster than the Xserver rendering, thus
filling up the X rendering pipes and essentially "locking up" the
Xserver (i.e. you can't even close the offending window because the
WM is starved too).

I verified this worked by making GtkSpinner paint multiple times on my
intel driver (which has some issue making this rendering slow atm),
and without this patch i get severe lag where even window dragging
stops for 5 seconds when i drag the mouse around. However, with the
patch everything is smooth.

https://bugzilla.gnome.org/show_bug.cgi?id=684639

ahodesuka/gtk,davidt/gtk,chergert/gtk,ahodesuka/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,jadahl/gtk,chergert/gtk,jigpu/gtk,jessevdk/gtk,davidgumberg/gtk,davidt/gtk,davidt/gtk,Sidnioulz/SandboxGtk,jigpu/gtk,grubersjoe/adwaita,grubersjoe/adwaita,ebassi/gtk,alexlarsson/gtk,Adamovskiy/gtk,alexlarsson/gtk,davidgumberg/gtk,jadahl/gtk,Lyude/gtk-,Adamovskiy/gtk,Distrotech/gtk2,Sidnioulz/SandboxGtk,ahodesuka/gtk,ahodesuka/gtk,jadahl/gtk,bratsche/gtk-,jadahl/gtk,jigpu/gtk,msteinert/gtk,davidgumberg/gtk,jadahl/gtk,msteinert/gtk,Lyude/gtk-,jessevdk/gtk,Lyude/gtk-,msteinert/gtk,alexlarsson/gtk,ahodesuka/gtk,Adamovskiy/gtk,jigpu/gtk,grubersjoe/adwaita,Sidnioulz/SandboxGtk,Lyude/gtk-,Sidnioulz/SandboxGtk,jessevdk/gtk,jigpu/gtk,alexlarsson/gtk,grubersjoe/adwaita,bratsche/gtk-,alexlarsson/gtk,jessevdk/gtk,bratsche/gtk-,grubersjoe/adwaita,ahodesuka/gtk,davidt/gtk,alexlarsson/gtk,Adamovskiy/gtk,ebassi/gtk,davidgumberg/gtk,chergert/gtk,Distrotech/gtk2,ahodesuka/gtk,davidgumberg/gtk,chergert/gtk,Distrotech/gtk2,jadahl/gtk,davidt/gtk,Lyude/gtk-,jigpu/gtk,bratsche/gtk-,msteinert/gtk,Adamovskiy/gtk,chergert/gtk,ebassi/gtk,chergert/gtk,davidgumberg/gtk,ebassi/gtk,Adamovskiy/gtk,msteinert/gtk,Adamovskiy/gtk,Lyude/gtk-,jessevdk/gtk,ebassi/gtk,Distrotech/gtk2,davidgumberg/gtk,Distrotech/gtk2,jessevdk/gtk,davidgumberg/gtk,ahodesuka/gtk,jadahl/gtk,chergert/gtk,jigpu/gtk,ebassi/gtk,jigpu/gtk,Sidnioulz/SandboxGtk,jadahl/gtk,davidt/gtk,bratsche/gtk-,msteinert/gtk,bratsche/gtk-,jessevdk/gtk,chergert/gtk,alexlarsson/gtk,Lyude/gtk-,Adamovskiy/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita,Distrotech/gtk2