gdk_x11_display_make_gl_context_current: move some code
gdk_x11_display_make_gl_context_current: move some code

This moves the code related to the frame sync code into
the is_attached check, which means we don't have to ever
run this when making non-window-paint contexts current.

This is a minior speed thing, but the main advantage
is that it makes making a non-paint context current
threadsafe.

chergert/gtk,alexlarsson/gtk,alexlarsson/gtk,davidgumberg/gtk,jadahl/gtk,Lyude/gtk-,davidgumberg/gtk,jigpu/gtk,jigpu/gtk,davidgumberg/gtk,grubersjoe/adwaita,jigpu/gtk,Adamovskiy/gtk,Adamovskiy/gtk,davidgumberg/gtk,jadahl/gtk,grubersjoe/adwaita,ahodesuka/gtk,davidgumberg/gtk,Lyude/gtk-,davidgumberg/gtk,grubersjoe/adwaita,Adamovskiy/gtk,alexlarsson/gtk,jigpu/gtk,alexlarsson/gtk,chergert/gtk,ahodesuka/gtk,Lyude/gtk-,Lyude/gtk-,Lyude/gtk-,jigpu/gtk,ahodesuka/gtk,chergert/gtk,jadahl/gtk,alexlarsson/gtk,ahodesuka/gtk,jigpu/gtk,jadahl/gtk,grubersjoe/adwaita,jigpu/gtk,grubersjoe/adwaita,jadahl/gtk,Lyude/gtk-,Adamovskiy/gtk,alexlarsson/gtk,ahodesuka/gtk,chergert/gtk,chergert/gtk,Lyude/gtk-,ahodesuka/gtk,Lyude/gtk-,Adamovskiy/gtk,jadahl/gtk,Adamovskiy/gtk,grubersjoe/adwaita,davidgumberg/gtk,jadahl/gtk,davidgumberg/gtk,chergert/gtk,chergert/gtk,Adamovskiy/gtk,alexlarsson/gtk,ahodesuka/gtk,grubersjoe/adwaita,Adamovskiy/gtk,chergert/gtk,ahodesuka/gtk,jadahl/gtk,jigpu/gtk,grubersjoe/adwaita,alexlarsson/gtk