narrow: extract wdir cleanup function to make it extensible We have an overlay filesystem which shows the entire repository, and unlinking a file that's in the underlying data store will create "tombstone" entries, which are going to cause our automatic tracking to re-add these directories. We need to use a different (non-posix) interface to clean up items in the working directory that are no longer relevant. Extracting this to a function lets us use extensions.wrappedfunction and perform this cleanup work, even if the paths aren't in the dirstate (they may have been removed in the past and thus entirely "tombstone" entries already, part of hgignore, exclusively directories (possibly empty), or other edge cases). Differential Revision: https://phab.mercurial-scm.org/D4681