clib2 Code

- Extended the thread-safety locking to the file descriptors.

- The thread-safety code is now subject to conditional compilation.
Both the library and the user code need to be rebuilt with the
preprocessor symbol __THREAD_SAFE defined to get thread-safe
code.

- Added more semaphore locking around the basic stdio, memory, locale
and dirent data operations. That should do it! While the library is
not reentrant (this is not ixemul.library) it should be thread-safe
now. Thread-safe in the sense of POSIX 1003.1c-1995.

- Added stdio thread locking functions flockfile(), funlockfile(),
and ftrylockfile().

- Modified the internal FILE structure to allow for thread locking.
Note that this again requires that the library is rebuilt!

- Added or modified macros for getc_unlocked(), getchar_unlocked(),
putc_unlocked() and putchar_unlocked().

- Added rand_r().

- Added flockfile()/funlockfile() wrappers around all stdio
functions.

- The process window pointer is now restored and reset between ^C
checks while wildcard patterns are expanded in the the command line.

- When using the wildcard expansion code for command line
parameters (which is by default linked in with libunix.a),
regular expressions can no longer prompt dos.library requesters
to appear. However, to be on the safe side, if you are expecting
to pass regular expressions on the command line, do not use
the wildcard expansion code such as by overriding the library
symbols with dummy functions such as are used in the file
"stdlib_wildcard_expand.c".

- Added a new variable '__open_locale' which can be used to
restrict all library functions to use the "C" language locale
rather than the current system locale settings. In addition
to that, two new functions __locale_exit() and __locale_init()
can be used to close and (re-)open the system locale at a
later time.

- Local ("static") functions are now identified by the STATIC
qualifier. This was done in preparation for changes that will
deal with global and local data and the issue of thread safety.

- Fixed a warning for a possibly uninitialized variable in the new iob hook
code.

- Cosmetic changes for (hopefully) better readability.

- The lseek() function return code was not consistently treated as the
then current file position. Fixed.

- Numerous house-keeping changes.

- The buffered and unbuffered file hook code is now invoked through
function pointers alone. The utility.library/CallHookPkt mechanism
is no longer required.

- Moved the entire lseek() code relevant for files into the hook
function.

- Simplified the close() function which now just calls into the
hook code to perform whatever is necessary. The hook code is
responsible for cleaning up after aliases, etc. This change in
turn made it possible to greatly simplify the hook code for
buffered files which now bypasses close/read/write/lseek and
directly invokes the hook code for unbuffered files.