xwayland: Fix hidden cursor

If a cursor is set when bits->emptyMask is true, the xserver
sets a NULL cursor instead.

Signed-off-by: Trevor McCort <tjmccort@gmail.com>
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.
xkb: Factor out a function to copy a keymap's controls unto another
xwayland: Handle keymap changes