These methods allow us to set and get xkbcommon keymaps as well as
locking a specific layout in a layout group.
With this, we introduce dependencies on xkeyboard-config, xkbfile,
xkbcommon-x11 and a libX11 new enough to have xcb support.
https://bugzilla.gnome.org/show_bug.cgi?id=734301
This reverts commit 3b85e4b2b9.
This breaks touch support; reverting would break wayland
(is what this patch tried to fix; we should find a better solution
that works on both).
This makes Alt+F7 / Alt+F8 work respectively under X11 nested mode.
For the native backend implementation, we'll need a special Clutter
function, so don't implement that for now.
