Use standard names for subpools and iterpools.

* subversion/bindings/swig/ruby/libsvn_swig_ruby/swigutil_rb.c
  (invoke_callback): rename sub_pool to subpool

* tools/dev/fsfs-reorg.c
  (get_combined_window): ditto; rename iter_pool to iterpool

* tools/server-side/fsfs-stats.c
  (get_combined_window): same here
  (parse_dir): rename iter_pool to iterpool

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1533971 13f79535-47bb-0310-9956-ffa450edef68