cleanup: fix leakage of dirstate._map to client code

We already had proper accessors for most of the behavior of
dirstate._map that callers cared about exposed in the actual dirstate
class as public methods. Sigh.

There are two remaining privacy violations in the codebase after this change:

 1) In the perf extension, which I suspect has to stick around because
    it's really testing the dirstate implementation directly

 2) In largefiles, where we deal with standins and mutating status. Looking at
    this, I _strongly_ suspect a formal dirstate interface would allow
    this to work via composition instead of inheritance and
    monkeypatching. Fortunately, such wins are a part of my motivation
    for this work. I anticipate we'll come back to this in due time.

Differential Revision: https://phab.mercurial-scm.org/D6837

hgext/largefiles/reposetup.py

@@ -234,7 +234,7 b' def reposetup(ui, repo):'
                     result[2] = [f for f in result[2]
                                  if f not in lfdirstate]
 
-                    lfiles = set(lfdirstate._map)
+                    lfiles = set(lfdirstate)
                     # Unknown files
                     result[4] = set(result[4]).difference(lfiles)
                     # Ignored files

mercurial/debugcommands.py

@@ -751,7 +751,7 b' def debugstate(ui, repo, **opts):'
         keyfunc = lambda x: (x[1][3], x[0]) # sort by mtime, then by filename
     else:
         keyfunc = None # sort by filename
-    for file_, ent in sorted(repo.dirstate._map.iteritems(), key=keyfunc):
+    for file_, ent in sorted(repo.dirstate.iteritems(), key=keyfunc):
         if ent[3] == -1:
             timestr = 'unset               '
         elif nodates:

mercurial/scmutil.py

@@ -319,7 +319,7 b' class casecollisionauditor(object):'
     def __init__(self, ui, abort, dirstate):
         self._ui = ui
         self._abort = abort
-        allfiles = '\0'.join(dirstate._map)
+        allfiles = '\0'.join(dirstate)
         self._loweredfiles = set(encoding.lower(allfiles).split('\0'))
         self._dirstate = dirstate
         # The purpose of _newfiles is so that we don't complain about