premute signals on binaries

[Guy Harris]

>This inconsistancy should eventually disappear, in about a year, when both
>companies move up to Sys V, r4, which will specify a binary standard for these
>signals, forcing one (or the other or both) to redo theses #define's.

In case anybody's curious, it appears as if SCO wins and Interactive
loses; according to the S5R4 manual, SIGSTOP is 23, SIGTSTP is 24, and
SIGCONT is 25.  SIGTTIN and SIGTTOU are 26 and 27.