build machine because that feature offsets the performance timings. We ignore
that check, however, because with binaries being pre-built on Hydra those
timings aren't accurate for the local machine in the first place. The build log
might show something such as the following:
| It appears you have cpu throttling enabled, which makes timings
| unreliable and an ATLAS install nonsensical. Aborting.
| See ATLAS/INSTALL.txt for further information
| Ignoring CPU throttling by user override!
svn path=/nixpkgs/trunk/; revision=32506
