Add svn_fs_info_config_files().

* subversion/include/svn_fs.h
  (svn_fs_info_config_files): New declaration.
  (svn_fs_info_t): Remove corresponding member.

* subversion/libsvn_fs/fs-loader.c
  (svn_fs_info_config_files): New definition.

* subversion/libsvn_fs/fs-loader.h
  (fs_vtable_t.info_config_files): New vtable member.

* subversion/libsvn_fs_base/fs.c
  (base_bdb_info_config_files): New implementation.
  (fs_vtable): Wire it in.

* subversion/libsvn_fs_fs/tree.h
  (svn_fs_fs__info_config_files): New declaration.

* subversion/libsvn_fs_fs/fs_fs.c
  (svn_fs_fs__info_config_files): New implementation.

* subversion/libsvn_fs_fs/fs.c
  (fs_vtable): Wire it in.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1465286 13f79535-47bb-0310-9956-ffa450edef68