largefiles: fix typo with s/__class/__class__/

Commit f78252429e0a (largefiles: don't create chain of __contains__
calls, 2015-03-11) introduced a typo with __class instead of
__class__. Let's fix it.

There are (obviously) no tests covering this code path, and I could
not figure out a way to trigger it, so it remains untested.

Spotted by Drew Gottlieb.

hgext/largefiles/reposetup.py

@@ -44,7 +44,7 b' def reposetup(ui, repo):'
                         return [lfutil.splitstandin(f) or f for f in filenames]
                     def manifest(self):
                         man1 = super(lfilesctx, self).manifest()
-                        class lfilesmanifest(man1.__class):
+                        class lfilesmanifest(man1.__class__):
                             def __contains__(self, filename):
                                 orig = super(lfilesmanifest, self).__contains__
                                 return (orig(filename) or