2) Use CURSIG(curproc) in PROCESS_ABORTING instead of junk code was there.
3) Reanimate timeout code in DO_SLEEP by setting WK_TIMEOUT flag
which is never set in old code.
4) DO_SLEEP: set aborting flag on interrupting singnals as supposed, not
on signals which do nothing as in old code.
5) Cleanup WAKE_UP macro, WK_WAKEUP not used.
6) Remove wrong typecasts in sleep/wakeup code.