vchoi_fork

[svn-r11733] Purpose:
    Code cleanup

Description:
    Added some comments about the thread-specific memory for the error and
function stacks.

    Changed H5close() to not use the function stack (since it causes it to
be re-enabled after shutting it down)

    Changed thread-safe semaphore code to not use dynamicly allocated memory.

Platforms tested:
    FreeBSD 4.11 (sleipnir)
    Linux 2.4
    Too minor to require h5committest