[IronPython] pybench support for IronPython

[Anthony Baxter]

If you apply patches www.python.org/sf/1563842 and
www.python.org/sf/1563844, you can run the pybench benchmark under
IronPython. It requires a patched version of platform.py (the first of
the two patches) and a patched version of Pybench. The latter is
available in the Python source tree in Tools/pybench.

Under Mono, I see overall that IronPython runs about 1/3 the speed of
CPython overall. There's some tests where it's faster, and some where
it's 20-30 times slower. I'd be curious if someone with .Net wanted to
try it there and compare against Python 2.5.

Anyway, if you're interested in potential targets for optimisation,
this could be a useful tool. It's certainly more useful than pystone
(which should be expunged from the universe as a useless benchmark).
More importantly, it shows a number of places in Mono that could use
some serious love and attention.