Begin switching the FSFS stats code to using the two-pool paradigm.
Rename existing pools that are either RESULT_POOL or SCRATCH_POOL
accordingly.

* subversion/libsvn_fs_fs/stats.c
  (get_file_size): The pool is used for tempories only.
  (initialize_largest_changes): All allocations are part of the result.
  (parse_representation,
   read_noderev,
   parse_dir): That pool is actually a RESULT_POOL.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1639430 13f79535-47bb-0310-9956-ffa450edef68