Parse and evaluate the FSFS config file once and store the individual
values in the private data struct.  We then no longer need to keep the
redundant svn_config_t instance around.

The only user of the config file is / was the cache configuration.
We move that bit to read_config() and extend fs_fs_data_t accordingly.

* subversion/libsvn_fs_fs/fs.h
  (fs_fs_data_t): Replace the CONFIG with the bits that we used to
                  read later from it but will now read immediately
                  with the rest of the settings.

* subversion/libsvn_fs_fs/fs_fs.c
  (read_config): Switch to two-pool paradigm to make FS->POOL available.
                 CONFIG is now a temporary and we need to fill more bits
                 in the FFD struct - code taken from caching.c:read_config.
  (svn_fs_fs__open,
   svn_fs_fs__create): Pass both, the FS->POOL as well as the temp POOL
                       to read_config.

* subversion/libsvn_fs_fs/caching.c
  (read_config): Remove the config struct access here.  Only process
                 settings passed to the FS struct here (no FSFS internals).
  (svn_fs_fs__initialize_caches): Get the info from the FFD struct now.

* subversion/libsvn_fs_fs/hotcopy.c
  (hotcopy_create_empty_dest): No CONFIG member to copy anymore.  The new
                               FFD members are not relevant for hotcopy.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1589235 13f79535-47bb-0310-9956-ffa450edef68