Switch FSFS index.c internal functions to using two pools.

Even though the callers will eventually pass the same pool to both
parameters, this still gives better readability / documentation and
is consistent with what we do elsewhere in this module.

* subversion/libsvn_fs_fs/index.c
  (get_l2p_header_body): Have two pool parameters now.  Writing to the
                         cache needs only a temporary pool.
  (get_l2p_page_info): Update caller.
  (get_l2p_header): Add SCRATCH_POOL parameter as we can now pass it
                    through to a sub-function.
  (svn_fs_fs__l2p_get_max_ids): Update caller.
  (get_p2l_header): Have two pool parameters now.  Writing to the cache
                    needs only a temporary pool.
  (get_p2l_page_info): Update caller.
  (get_p2l_entry_from_cached_page): Have two pool parameters now.  Only
                                    the returned object needs to be
                                    allocated in the RESULT_POOL.
  (p2l_entry_lookup_func,
   p2l_get_max_offset): Update callers.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1626886 13f79535-47bb-0310-9956-ffa450edef68