gmp-6.0.0a tuneup aborts computing HGCD_THRESHOLD

[Torbjörn Granlund]

I'm afraid that the tuneup program is not 100% stable.  In particular,
GCD measuring tends to be non-reproducible.  We don't consider this to
be a critical GMP problem, so we have not given it priority.

If you want to volunteer the time required to understand and fix this
problem, you're most welcome.

-- 
Torbjörn
Please encrypt, key id 0xC8601622