[MLton] cygwoes

[Stephen Weeks]

> > With your fix of gc.c line 1319, do all the regressions pass even
> > without use-mmap? 
>
> I can't even get a working compiler on Cygwin, even with the change to 
> line 1319 of gc.c.

You don't need one.  The regression script has a couple of flags
(-cross, -run-only) that make it pretty easy to "cross run" the
regressions by compiling them down to C, shipping them to the target
machine, and then compiling to exe and running there.  I always do
that before trying to bootstrap on a new/buggy platform.