Make more functions static.
tty.c:
Use tcflag_t (u_long) and cc_t instead of u_char and int/long.
Don't record values that are only evaluated once.
Compare ints using imin(), not min(). min() is for comparing u_ints.
Old versions of tty.c used the type-safe but multiple-evaluation-unsafe
macro MIN(). The args are apparently never negative; otherwise this
change would be non-cosmetic.
Don't repeat the loop test in ttywait().
tty.h:
Improve English in and formatting of comments.