[Cython] Hudson pyregr testing takes too long

[Stefan Behnel]

Hi,

I just noticed that the CPython pyregr tests have jumped up from ~14 
minutes for a run to ~4 hours when we added generator support.

https://sage.math.washington.edu:8091/hudson/view/cython-devel/job/cython-devel-tests-pyregr-py26-c/buildTimeTrend

I currently have no idea why that is (well, it's likely because we compile 
more tests now, but Vitja's branch ran the tests in ~30 minutes). It would 
be great if someone could find the time to analyse this problem. The 
current run time makes it basically impossible to keep these tests enabled.

Stefan