On the fsx-1.10 branch: Further reduce the costs of creating a svn_fs_x__revision_file_t. We will often not need to access it due to caching.
On the fsx-1.10 branch:
Further reduce the costs of creating a svn_fs_x__revision_file_t.
We will often not need to access it due to caching.

* subversion/libsvn_fs_x/rev_file.c
  (svn_fs_x__revision_file_t): Add OWNER pool and create the local POOL
                               only lazily.  This saves time and RAM.
  (create_revision_file): Update constructor.
  (get_file_pool): New utility function.
  (open_pack_or_rev_file,
   auto_open): Use the new utility to access the file pool.
  (svn_fs_x__close_revision_file): POOL may be NULL now.


git-svn-id: 40002ad72c45bcd78a61b73a7ab5afec77c4e304@1663239 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion