 * Use mmap() to store the mutex, condition variable, and counter in a
   process-shared mapping at $HOME/.pthread_workqueue. Mark the mutex
   and condition variable as process-shared.
   -or-
   Use a named semaphore at /pthread_workqueue.$UID
   -or-
   Write a kernel device driver for /dev/pthread_workqueue that will
   allow threads to select() for readiness to achive global load balancing.

 * Support Debian/kFreeBSD in the configure script.
