GCC headers and DJGPP port

[Mike Stump]

> From: Zack Weinberg <zack@wolery.cumb.org>
> Date: Sat, 22 Jul 2000 16:02:26 -0700
> To: Mike Stump <mrs@windriver.com>

> A similar argument can be made for assert.h, stddef.h, and possibly
> float.h, but these headers do not cause nearly as much trouble as
> limits.h.  Limits.h must die.

If we do this, we should do them all enmass, and then be willing to
seek out and test on lots of platforms to make sure we don't introduce
new bugs.