Fix the dumb and sc terminal emulators to compile and work.
First remove ifdefs of the unsupported option SC_DUMB_TERMINAL which
prevented building using both in the same kernel and broke regression
tests. This option will be replaced by per-emulator supported options.
The dumb emulator rotted with KSE in r83366, but usually compiled since
it is ifdefed to nothing unless SC_DUMB_TERMINAL is defined. The type
of an unused function parameter changed.
Both emulators rotted when 2 new methods were added while the emulators
were removed. Only null methods are needed, but null function pointers
give panics instead.
The wildcard in the default for the unsupported option SC_DFLT_TERM
never really worked. It tends to prefer the dumb emulator when multiple
emulators are configured. Change it to prefer scteken for compatibility.
UnifiedSplitRaw
