Fix a pool bug in our entries walker.
Fix a pool bug in our entries walker.

Prevents some devious pool related bugs if you allocate long lived objects
in svn_wc_walk_entries3's svn_wc_entry_callbacks2_t.found_entry callback
and expect them to be allocated in the pool you passed to 
svn_wc_walk_entries3.

* subversion/libsvn_wc/entries.c
  (walker_helper): The first call to the
  svn_wc_entry_callbacks2_t->found_entry callback, for the '.' entry, passes
  the pool which is passed into this function, the same pool passed to its
  only caller svn_wc_walk_entries3.  But all subsequent found_entry callbacks
  use a subpool which, no surprise, is destroyed.  This is at odds with
  the doc string for svn_wc_walk_entries3 which states that it should use
  its POOL argument for "looping, recursion, and to allocate all entries
  returned".  So with this change we start using POOL for that and use the
  subpool only for temporary allocations.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@878263 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion