rhg: use openat library for more efficient filesystem access
@SimonSapin, this is a proof-of-concept patch I mentioned to you. It provides a large performance improvement in my benchmarks (in particular when running stat -mard), although I'm not entirely sure it's covered with tests.
It's not quite finished, in particular it doesn't handle the case when the filesystem doesn't return the file type. It also almost certainly doesn't work on Windows, but if we like the benchmarks then that can be worked out.
There seems to have been no activities on this Diff for the past 3 Months.
By policy, we are automatically moving it out of the need-review state.
Please, move it back to need-review without hesitation if this diff should still be discussed.