On the fsfs-format7 branch:  fix a major inefficiency in our pack file
placement / optimizaion code.  It accidentially placed all nodes that
use older base reps before continuing after with the latest / top level
data.  Effectively, the data needed for a HEAD checkout got spread over
the whole pack file(s).

Also, fix a pool usage issue along the way.

* subversion/libsvn_fs_fs/pack.c
  (pick_recursively): make sure that the represenation and node order
   is dictated top-down instead of bottom-up, i.e. recurse on noderev
   level instead of representation level
  (sort_reps): no need to limit the nodes placed in the second run
  (pack_log_addressed): use an iteration pool to keep open file count down

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1445051 13f79535-47bb-0310-9956-ffa450edef68