Removed YIELD call since we're waiting for ringbuf semaphore instead.

incom() now supports timeout parameter (defaults to 0).

(Ctrl-L).

each write), must define RINGBUF_SEM.

The semaphore emulation lib provides for sem_timedwait() which will allow
correct blocking calls to be used rather than bogus (On *nix anyways)
arbitrary 1-55ms (depending on hardware) wait during a loop to avoid 100%
CPU utilization.

The xpsem lib uses mutexes to provide semaphore functions and is taken
almost line-per-line from FreeBSD.  (copyright left intact)

**** WARNING ****
This commit was performed while drunk.  If this breaks your build, I
personally guarantee you get to keep all remaning pieces.

Note: Some systems do not have daemon() noteably Solaris... for these
systems, daemon() is in sbbscon... not sure if this will break any utils
ion those platforms or not.

problem where a click is sent to adjacent icons.

threadwrap.h where they belong.

threads.

tested on more OSs (Currently, the added functions fail on Linux)

to security, credits, etc. immediately effective.

compiled for anyone by me.

*Blush*

sem_trywait and sem_trywait_block need to return -1 on error and set errno.

Created (non-POSIX) sem_trywait_block implementation for Win32
(need to investigate/implement draft-POSIX sem_timedwait function).

Created MAYBE_YIELD macro to perform the function of a Sleep(0) on Win32
or sched_yield/pthread_yield on Unix (does not lower CPU utilization).

permanently locked under some circumstances on Win32.

deleted after QWK-packing.