xkb: Factor out a function to copy a keymap's controls onto another

Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
xkb: Repurpose XkbCopyDeviceKeymap to apply a given keymap to a device

This will also make it useful for cases when we have a new keymap to
apply to a device but don't have a source device.

Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
xkb: constify XkbDDXOpenConfigFile

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
xkb: add a callback to xkbcomp

This provides a callback to write to xkbcomp's buffer once everything is
prepared.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
xkb: factor out xkb loading to LoadXkm

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
xkb: add KeymapOrDefault

Helper function to return a default map if the keymap compilation failed.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
xkb: add XkbLoadKeymapFromString

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Merge remote-tracking branch 'whot/for-keith'