tests/test-filecache.py.out

osutil: write a C implementation of statfiles for unix

This makes a big difference to performance.

In a clean working directory containing 170,000 files, performance of
"hg --time diff" improves from 2.38 seconds to 1.69.

basic:

creating
creating
creating
creating

fakeuncacheable:

creating
creating
creating
creating
creating
creating