rust: remove support for `re2`...
rust: remove support for `re2`
With the performance issues with `regex` figured out and fixed in previous
patches and `regex` newly gaining support for empty alternations, there is no
reason to keep `re2` around anymore. It's only *marginally* faster at creating
the regex which saves at most a couple of ms, but gets beaten by `regex` in
every other aspect.
This removes the Rust/C/C++ bridge (hooray!), the `with-re2` feature, the
conditional code that goes with it, the documentation and relevant part of the
debug/module output.
Differential Revision:
https://phab.mercurial-scm.org/D8594
