- Update keymap to use reference keysym names.
- Fix x11comp test by handling old x11proto.
We need xkbcomp to be compiled with at least x11proto-dev 2023.2.
So we replace the unsupported keysyms with supported ones not
already in the keymap. This is kind of ugly, but it works. If we
ever want to restore the original keysyms with their supported names,
the substitute keysyms will be easy to spot.