clib2 Code

- More corrections and clarifications.

- Updated the copyright text.

- The printf() family stripped trailing zeroes from the integer part
of %g output. Fixed.

- Added "factorial" test program for "%g" testing.

- The __main() stub function expected by the 68k GCC build is no
longer part of "stdlib_main.c". This helps the C++ support, since the
__main symbol definition no longer clashes with the definition in
"libgcc.a".

- Preparations for release.

- Forgot to check in a file.

- Added another function called __reset_max_mem_stats() which will reset the
counters for "maximum amount of memory used" and "maximum number of chunks
allocated" to the current figures for these values.

- Fixed the alloca() declaration in <stdlib.h> so that software which keys
off the fact whether or not the alloca preprocessor symbol is defined
will do the right thing.

- Added an optional call-back function which can be called if alloca()
is about to return NULL, which some software does not consider.
Rather than letting such software drop into an illegal memory access
or worse, that call-back function will be invoked instead, which can
print an error message and eventually call abort().

- Fixed the header files I broke by mistake.

- You can now request that your program uses the clib2 alloca() function
rather than the built-in compiler alloca().

- alloca() is now part of libunix.a, too.

- Added notes on where to find documentation and updates to each header file.