This allows us to use both the old sun keyboard events (/dev/kbd) as
new wscons events (/dev/wskbd*).
TODO: Not implemented for the kbd at zstty attachment.
Wskbd as console does not yet work.
layers. Common middle layer shared by kbd_zs and sunkbd is moved into
the new file. Move shared config directives to files.sun and adjust
ports' files.* accordingly.
Need this to support console/Xsun on Mr.Coffee JavaStation.
Tested on sparc, sparc64 (by martin) and sun3 (by jdc).
