Pierre-Yves David <pierre-yves.david@octobus.net> [Fri, 01 Oct 2021 18:52:26 +0200] rev 48137
dirstatemap: create `_dirs_incr/_dirs_decr` methods on the common class
The Rust wrapper does not need them. However having a default, no-op,
implementation will help use to write code used by both implementation.
Differential Revision: https://phab.mercurial-scm.org/D11570