For application to HEAD, following community review.

For application to HEAD, following community review.

* Changes incorrect CYGWIN defines to __CYGWIN__

* Some localtime returns NULL checks (when unchecked cause SEGVs under
Win32
regression tests)

* Rationalized CreateSharedMemoryAndSemaphores and
AttachSharedMemoryAndSemaphores (Bruce, I finally remembered to do it);
requires attention.

Claudio Natoli