vfs: extract the audit path logic into a submethod This will make it possible to apply it in more cases.

subrepo-git: use an official origvfs when appropriate The origvfs has the auditor properly set and can move file without issue. The current code is currently working without errors because rename are not audited, yet.

revert: extract origvfs logic in a sub-function The subrepo's "revert" logic could benefit from it.

vfs: treat 'undo.' file the same as 'journal.' file They are the same kind of file, they are protected by the store lock, but directly lives inside the '.hg' directory. No warnings were ever raised about them because `vfs.rename` is not audited. Something we are trying to change.

perf: add a perfignore command The command is meant to benchmark operations related to hgignore. Right now the command is benchmarking the loading time of the hgignore rules.

py3: use pycompat.xrange instead of xrange xrange does not exists on Python 3. Differential Revision: https://phab.mercurial-scm.org/D5302

store: write fncache only once if there are both adds and removes Differential Revision: https://phab.mercurial-scm.org/D5307

perf: disable revlogs clearing in `perftags` by default This aligns things with what `perfbookmarks` does. I decided to disable the revlogs clearing by default to focus on the core logic by default, ignoring side effects. If we prefer to emphasize the side effect, we can instead keep this on in `perftags` and enable it by default in `perfbookmarks`.