Redesign and implement "fetch filesystem info".

Introduce a new function, svn_fs_info_format(), and delete from svn_fs_info_t
members for which retrieval functions already exist.

* subversion/include/svn_fs.h
  (svn_fs_info_format): New declaration.
  (svn_fs_info_t): Trim some members, as described above.

* subversion/include/svn_repos.h
  (svn_repos_info_format): Add cross-reference to svn_fs_info_format().

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

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

* subversion/libsvn_fs_base/fs.c
  (base_bdb_info_format): New function.
  (fs_vtable): Wire it in.

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

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

* subversion/libsvn_fs_fs/fs_fs.c
  (svn_version.h): Include.
  (svn_fs_fs__info_format): New definition.

* subversion/tests/libsvn_fs/fs-test.c
  (svn_version.h): Include.
  (test_fs_info_format): New test.
  (test_funcs): Run it.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1465153 13f79535-47bb-0310-9956-ffa450edef68