On the fsfs-format7 branch:  add optional debugging feature that writes
type and location of every data access to the console.

* subversion/libsvn_fs_fs/cached_data.c
  (dgb__log_access):  new debugging utility
  (svn_fs_fs__get_node_revision,
   create_rep_state_body,
   read_delta_window,
   svn_fs_fs__get_changes): hook debug function into all data access funcs

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1445058 13f79535-47bb-0310-9956-ffa450edef68