In preparation of having a single file containing rev data and indexes,
unify revision_file_t initialization:  Always open the rev file instead
of just initializing it and opening it upon demand.

* subversion/libsvn_fs_fs/rev_file.h
  (svn_fs_fs__init_revision_file): Drop.

* subversion/libsvn_fs_fs/rev_file.c
  (svn_fs_fs__init_revision_file): Rename to ..
  (init_revision_file): .. this as it's no longer an API.
  (svn_fs_fs__open_pack_or_rev_file): Update caller.

* subversion/libsvn_fs_fs/cached_data.c
  (dbg_log_access): Use "open pack file" instead of plain init
                    followed by later auto-open.  Update all
                    references to REV_FILE.
  (svn_fs_fs__check_rep): Same.

* subversion/libsvn_fs_fs/index.c
  (svn_fs_fs__l2p_get_max_ids): Same.

* subversion/libsvn_fs_fs/verify.c
  (compare_l2p_to_p2l_index,
   compare_p2l_to_l2p_index): Same.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1604417 13f79535-47bb-0310-9956-ffa450edef68