'cflag' for the console. Normally set to TTYDEF_CFLAG, may be
overridden by machine-dependent console attachment code, as necessary.
(Alpha uses it to set cs8 -parenb.) Files including comvar.h now
need to include <sys/termios.h>, because comconscflag is of type
tcflag_t.
substantial reworking of the multi-port drivers, as they need to frob
bits in the io-port spaces of their children. As a result, the
commulti->com attachment interface is substantially more complex.
(This may be fixable in the future by making some of the code common,
but as long as io-port allocation checking is planned, it's necessary.)
