cbreak mode in ESIX

[Guy Harris]

>>< 	stty -icanon min 1 time 0
>
>SCO xenix stty will set it to 1, ISC unix stty to 49.

Vanilla S5R3 and S5R3.1 "stty" behave the way ISC's does, so that's
probably whence ISC's "stty" got that behavior; many other S5R3.2
"stty"s will probably work that way as well.

SunOS 4.x's "stty" behaves the way SCO Xenix's does, and at least
according to the manual page S5R4's "stty" does so as well (that
behavior is the more sensible one; they're numbers, not characters, the
fact that they're stuff into members of an "unsigned char" array
nonwithstanding).