Switch the remainder of the FSFS stats code to two-pool paradigm.

* subversion/libsvn_fs_fs/stats.c
  (read_phys_pack_file,
   read_phys_revision_file): Use 2 pool parameters and drop the local.
  (read_item): Use 2 pool parameters.
  (read_log_rev_or_packfile): Same. Drop the local pool.
  (read_log_pack_file,
   read_log_revision_file): Two-pool paradigm pass-through.
  (read_revisions): Use 2 pool parameters and a proper ITERPOOL.
  (svn_fs_fs__get_stats): Update caller.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1639549 13f79535-47bb-0310-9956-ffa450edef68