On the fsfs-format7 branch: make svn_fs_fs__path_rev_absolute return the
path instead of error objects because there are no error conditions.
Use this simplified API to implement two new FSFS file name constructors.

* subversion/libsvn_fs_fs/fs_fs.h
  (svn_fs_fs__path_rev_absolute): return path directly
* subversion/libsvn_fs_fs/util.h
  (path_l2p_index,
   path_p2l_index): declare new path naming function

* subversion/libsvn_fs_fs/fs.h
  (PATH_EXT_L2P_INDEX,
   PATH_EXT_P2L_INDEX): define file extensions for our new index files
* subversion/libsvn_fs_fs/util.c
  (path_l2p_index,
   path_p2l_index): implement new path naming function
  (svn_fs_fs__path_rev_absolute): implement changed API

* subversion/libsvn_fs_fs/fs_fs.c
  (svn_fs_fs__open_pack_or_rev_file): update caller
* subversion/libsvn_fs_fs/revprops.c
  (set_revision_proplist): ditto
* subversion/libsvn_fs_fs/transaction.c
  (commit_body): same here


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1430675 13f79535-47bb-0310-9956-ffa450edef68