Replace conformtest.pl with conformtest.py [committed]

[Florian Weimer]

* Joseph Myers:

> Continuing the consolidation on Python for various miscellaneous build
> and test scripts, this patch moves conformtest from Perl to Python.

For me, this increases test time for conform/ from 97 seconds to
126 seconds, perhaps due to the increased startup overhead of Python
compared to Perl.

Is there a way we can recover some of the additional overhead?  Perhaps
by doing more work in a single Python invocation?

Thanks,
Florian