[MLton] x86_64 branch on AIX

[Ville Laurikari]

Hi,

I've successfully bootstrapped the compiler on AIX 5.2, and all
regressions pass.

There were some changes mostly to platform/aix.[ch], and one to
cenv.h.

The change to cenv.h was that I moved the n-way OS ifdef before the
n-way arch ifdef.  This was necessary since it seems that on AIX there
is no predefined cpp definition available to detect the current
architecture (at least I couldn't find one, that's why aix.h contains
"#define __ppc__").

It seems that the system headers (or GCC headers?) on AIX are broken
and have CHAR_MIN defined to 0, although `char' _is_ signed, at least
with GCC.  I fixed this with

  #undef CHAR_MIN
  #define CHAR_MIN -128

in aix.h, but I'm wondering if you guys can think of a better way?  Is
that test really needed?  Are there actually places which assume that
`char' is signed?

--
http://www.iki.fi/vl/