[DotGNU]MacOSX works!

[Rhys Weatherley]

Due to the generous donation of a MacOSX login from
Brandon Bremen, I have now got the MacOSX version of
Portable.NET to a useful working stage.

All of the tests in "samples" work, as does "cscctest"
and PNetMark.

A few notes:

- The compile spits out a huge number of errors when
  building "engine/cvm.c".  Then it ignores them and
  keeps going.

  This problem is due to Darwin's "smart" C pre-processor
  which is not smart enough to understand my inimitable
  macro dog's breakfast in the CVM interpreter core. :-)

  (Actually, it isn't really my fault - the "smart" mode
  does not understand computed gotos, which is a bug in
  the C pre-processor).

  When the pre-processor dies, it backs off to "basic"
  mode and the compile continues OK.  I haven't yet
  discovered which gcc option turns off smart mode
  completely (suggestions welcome).

- The test_varith.c file causes Brandon's machine to just
  stop dead.  This is probably due to the complexity of
  this file - I'll endeavour to simplify or split it.
  Just ^C the build at this point - its nearly finished
  anyway.

- There were a number of alignment and endian issues
  that cropped up, that I've now fixed.  This should help
  other non-x86 platforms such as sparc and hpux.

- I made some slight changes to the autotools system to
  support automake 1.5.  This may help Cygwin users who
  have been having problems with 1.5 (or it may not: try
  it and see).

To build, do the following:

- Check out a fresh pnet tree from CVS
- ./auto_gen.sh
- ./configure
- make

Cheers,

Rhys.