tuneup crash after proper libgmp build/check/install on Macbookpro11 (Haswell/AVX2) Mavericks

[Torbjorn Granlund]

There can be several causes for tuneup's timing problems.  Poor cycle
counter management in the operating system kernel is perhaps always the
root cause.  I don't know how Apple's Darwin kernel work on x86 in that
respect.  Unfortunately, the popular kernel Linux works really poorly in
this respect.

For such problem systems, making sure the system is minimally loaded can
help.


Torbjörn