clib2 Code

- Fixed the constructor/destructor invocation sequence for the SAS/C and
GCC 68k library builds.

- Modified the SAS/C constructor/destructor invocation sequence, now that
the names of the functions assigned through the new macros are different.

- Turns out that the constructor/destructor calling sequence
was still wrongish for the OS4 library. So I had to change
it *again*. Which probably means that the 68k library will
need further changes...

- assertion failures early on during program initialization
should no longer spell big trouble on account of the stdio
data structures possibly not being in a well-defined and
initialized state.

- Moved the call chain printing out of stdlib_main.c and into
separate files.

- Removed some more redundant data from stdlib_main.c.

- Added the first real C99 function: _Exit().

- Reorganized the local header files, removing redundancies.

- Dropped unused stub code which is now redundant because of
the constructor/destructor mechanism.

- fcntl() did not work for sockets. Fixed.

- Re-added the long word alignment check for MC68020 I didn't commit
at home.

- ftruncate() ended up changing the current file position, contrary
to what it is supposed to do. Fixed.

- Turns out that the 68k GCC port does not sort constructor and
destructor functions in any way at all. I reimplemented the
entire library constructor/destructor functionality to use the
same approach as libnix.