Nightly GMP builds

[Torbjorn Granlund]

The GMP nightly builds will be testing GMP 5.0 for a some days now,
meaning that http://gmplib.org/devel/testmachines.shtml will reflect the
status of http://gmplib.org:8000/gmp-5.0/.

Please remain aware of this when you push things to the mainline
repo--there will be no broad, automated testing of your changes for now.

Commiters: You are welcome to help moving bug fix changes and
(conservative) portability changes from the mainline repo to the gmp-5.0
repo.  If in doubt, please ask this list.

-- 
Torbjörn