x11/libxkbcommon: expose Wayland support in xkbcli

$ xkbcli interactive-wayland
seat0: keysyms [ h ] unicode [ h ] layout [ English (US) (0) ] level [ 0 ] mods [ ] leds [ ]
seat0: keysyms [ i ] unicode [ i ] layout [ English (US) (0) ] level [ 0 ] mods [ ] leds [ ]

Approved by: manu
Differential Revision: https://reviews.freebsd.org/D29664