[PATCH] Enforce GMP/MPFR version requires and fix fortran/28276,27021

[Richard Kenner]

> One argument against this is that it then becomes possible for two
> maintainers to approve each others patches.  While true, I don't see
> that as significantly more risky than the current situation.  

And even so, it's still valuable to have two people look at something instead
of one.

> It is still important to pick trustworthy people.

Sure, but with that sort of an approach, you can get away with trusting them
a little less.  It's like the "two man rule" in the military with nuclean
weapons: *nobody* is trusted enough to be alone with one.