project: Set config option to skip lfs process filter

During sync, repo runs `git read-tree --reset -u -v HEAD` which causes
git-lfs's smudge filter to run, which fails because git-lfs does not
work with bare repositories.

This was fixed in I091ff37998131e2e6bbc59aa37ee352fe12d7fcd to
automatically disable this smudge filter. However, later versions of
Git (2.11.0) introduced a new filter protocol [1], to avoid spawning
a new command for each filtered file. This was implemented in Git-LFS
1.5.0 [2].

This patch fixes the issue by setting the git lfs process filter, in
addition to the smudge filter. For any projects that have LFS objects,
`git lfs pull` must still be executed manually afterwards.

[1] https://github.com/git/git/commit/edcc85814c87ebd7f3b1b7d3979fac3dfb84d308
[2] https://github.com/git-lfs/git-lfs/pull/1617

Bug: https://crbug.com/gerrit/10911
Change-Id: I277fc68fdefc91514a2412b3887e3be9106cab48

project.py

@@ -2399,6 +2399,7 @@ class Project(object):
           if m.Has(key, include_defaults=False):
             self.config.SetString(key, m.GetString(key))
         self.config.SetString('filter.lfs.smudge', 'git-lfs smudge --skip -- %f')
+        self.config.SetString('filter.lfs.process', 'git-lfs filter-process --skip')
         if self.manifest.IsMirror:
           self.config.SetString('core.bare', 'true')
         else: