clib2 Code

- 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.

- Added a table size check to guard against accesses beyond the last
file descriptor.

- Aliases of file descriptors are now using the signal semaphore
of the original file descriptor.

- close() did not return 0 if the file descriptor in question
was really just an alias. Fixed.

- Added a feature which makes it possible to have several clients
use the standard I/O streams (stdin/stdout/stderr) and have these
referring to their process' Input()/Output()/ErrorOutput()
streams. This is intended to support the upcoming shared
library feature.

- Fixed the SAS/C destructor function prototypes and verified
that the constructors/destructors are called in the proper
order, too.

- The destructor function invocation code no longer calls
setjmp(). This is now done within stdlib_main.c prior to
calling the destructor function invocation code.

- Switched over the startup code and the library itself to use
constructor/destructor functions for initialization and cleanup
purposes.

This commit was manufactured by cvs2svn to create tag
'BEFORE_CONSTRUCTOR_CHANGE'.

- Introduced new constructor types and changed the overall priority
order.

- Moved data out of stdlib_data.c and into the code that references
or initializes it.

- The stdlib constructor now performs the CPU/FPU compatibility test.

- The macro definitions deserved better documentation. Well, they probably still do...