[MLton] building mlton on Solaris 10

[Gergely Buday]

> So, I'm still confused by the fact that you are producing the expected
> sizes for sparc-solaris, bt the regression script is comparing against
> mlton.share.ok.

Vaguely I remember that in the beginning the regression script did not
find bin/platform for some reasons, that could explain this.

I'll do the regression again once I get a working 32-bit gmp on my
Solaris box. Unfortunately the one on sunfreeware.com is 64-bit. I'm
getting error messages about bad so's.

- Gergely