clib2 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...

- Fixed another interesting bug in the OS4 destructor code.

- Corrected a typo in the OS4 destructor code.

- Added S_IREAD, S_IWRITE and S_IEXEC aliases to <sys/stat.h>.

- Reimplemented the constructor/destructor invocation code for GCC.
Both the 68k and PowerPC platform now invoke them in the same order
and the 68k code uses the designated invocation priorities. The
PowerPC destructor function now sets up the exit() jmp_buf before
the destructor functions are called.

- Reworked the constructor/destructor macros again.