largefile: use `update_file` for `synclfdirstate` "n" case
This is the newer, more semantic API.
Differential Revision: https://phab.mercurial-scm.org/D11166
largefile: replace the `normallookup` call when creating a new lfdirstate
This is the newer, more semantic API.
Differential Revision: https://phab.mercurial-scm.org/D11165