display: Add display to displaymanager later
display: Add display to displaymanager later

Instead of GdkDisplay::init, only add the display to the display manager
in GdkDisplay::opened. This avoids spurious changes of the default
display in gtk_init() when we're trying to find the one that works and
try to open lots of different ones.

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