sleep writearound/system call

[utzoo!decvax!ucbvax!unix-wizards]

>From decvax!duke!unc!smb at Berkeley Thu Nov 12 00:36:42 1981
In-real-life: Steven M. Bellovin

In v7, there is no sleep system call.  Also, the v6 scheme failed badly
if the clock was reset, especially if it was reset backwards.  Cron,
for example, wouldn't run until the tod clock matched what was calculated
when the sleep call was issued.  Ditto for update.  The real solution
is probably to use the Berkeley signal stuff.