D2572: xdiff: vendor xdiff library from git

[ryanmce (Ryan McElroy)]

ryanmce added a subscriber: quark.
ryanmce added a comment.


  To be clear, this patch series was created by @quark, but phabricator did not keep the author information from the patches.
  
  I've ported it here to generate discussion about this as a path forward.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2572

To: ryanmce, #hg-reviewers
Cc: quark, mercurial-devel