largefiles: delete unnecessary meddling with matcher internals

lfutil.getstandinmatcher() was setting match._always to False because
it wanted a matcher of no patterns to match no files and match.match()
instead matches everything. However, since ba8089433090 (largefiles:
ensure lfutil.getstandinmatcher() only matches standins, 2015-08-12),
it never actually passes an empty list of patterns, so the hack has
become unnecessary.

hgext/largefiles/lfutil.py

@@ -296,8 +296,6 def getstandinmatcher(repo, rmatcher=Non
         if not pats:
             pats = [wvfs.join(standindir)]
         match = scmutil.match(repo[None], pats, badfn=badfn)
-        # if pats is empty, it would incorrectly always match, so clear _always
-        match._always = False
     else:
         # no patterns: relative to repo root
         match = scmutil.match(repo[None], [wvfs.join(standindir)], badfn=badfn)