On the fsfs-format7 branch:  speed up directory cache access by changing
addressing from fs_id to the rev,item keys used for most data.  This
further reduces the DAG access / traversal overhead.

Unfortunately, this will only work for committed data, i.e. when rev>=0.
We are stuck with the fs_id-based cache for txn data.

* subversion/libsvn_fs_fs/cached_data.c
  (parse_dir_entries): unparse fs_id only in case of an error
  (locate_dir_cache): construct the required key as well
  (svn_fs_fs__rep_contents_dir,
   svn_fs_fs__rep_contents_dir_entry): update callers

* subversion/libsvn_fs_fs/caching.c
  (svn_fs_fs__initialize_caches): update key info


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1443182 13f79535-47bb-0310-9956-ffa450edef68