Changed URL for benchmark graphs

[Neil Jerram]

With apologies for the churn... my benchmark graphs are now back at
http://ossau.homelinux.net/~neil.  (i.e. they've moved back from port
8000 to port 80.)

Also they haven't been auto-updating, since yesterday, because I've been
trying to investigate why so many individual benchmarks have apparently
been reporting 0 time for a while.  I hope to understand that soon, and
fix it if a fix is needed, and then the auto-updating will resume.

Thanks,
        Neil