Basic benchmarks

[Michael Hope]

I've been checking over the benchmarks as a lead up to the 2010.09
release.  We're in a good way compared to both 4.4.4 and 4.5.1 for
most non-trivial tests.
 * pybench is 10.9 % faster than 4.4.4 and 7.7 % faster than 4.5.1.
 * linpack is 46.4 % faster than 4.4.4 and the same as 4.5.1.
 * ffmpeg h.264 video decode (with hand written assembler versions
turned off) is 15.4 % faster than 4.4.4 and 1.2 % faster than 4.5.1.

All results are statistically invalid and against poor workloads, but
I'll work on that.

See http://ex.seabright.co.nz/helpers/benchcompare for more.

-- Michael