zstd: vendor python-zstandard 0.8.1
This contains a fix for compilation on BSDs.
#no-check-commit
https://bz.mercurial-scm.org/1089 $ hg init $ mkdir a $ echo a > a/b $ hg ci -Am m adding a/b $ hg rm a removing a/b (glob) $ hg ci -m m a $ mkdir a b $ echo a > a/b $ hg ci -Am m adding a/b $ hg rm a removing a/b (glob) $ cd bRelative delete: $ hg ci -m m ../a $ cd ..