The "libphutil" library is no longer distributed as a standalone library. Instead, it is now bundled with "Arcanist" and "Phabricator". For more information, see <https://phurl.io/u/libphutil>. If you are a normal user of Phabricator or Arcanist, you can delete the "libphutil/" directory. If you are a developer who has code with dependencies on "libphutil/", update your dependencies to point at "arcanist/" or "phabricator/" as appropriate.