Revision 1462413

In the FSFS "paranoid verify" code, disable caching.  See within for a question.

* subversion/include/svn_fs.h
  (SVN_FS_CONFIG_FSFS_CACHE_*): Add a note to maintainers who add such symbols.

* subversion/libsvn_fs_fs/fs_fs.c
  (verify_as_revision_before_current_plus_plus):
    Disable caches the API allows to disable, and add a question.