fully polyvariant self-compile

[Henry Cejtin]

I  went  to my friend Rico's place and used his machines with 4 gig of Ram to
compile a version of MLton without  using  the  -no-polyvariance  flag.   The
result  was  that  it compiled fine using a fixed heap of 2000m.  Then I used
the result to do a second self-compile, again with a  fixed  heap  of  2000m.
The  ratio of old time / new time was 1.4.  The ratio of new text size (i.e.,
the first number output by the size program) / old text size was also 1.4.

The size blow up is not great, but the speed up seems very fine to me.

All of this is with the 2001-03-21 version of MLton.  I'm quite certain  that
at  some  point in the past I tried to do a self compile on Siskind's machine
with 2 gig of RAM and it didn't fit,  so  some  change  in  the  compiler  is
clearly  at  least  partly  responsible.   (Note,  that  was a long time ago.
Certainly way before the native back end.)