On the log-addressing branch:  Generate and store the FNV checksums.
We don't use them for verification, yet.

* subversion/libsvn_fs_fs/transaction.c
  (fnv1a_stream_baton_t,
   fnv1a_write_handler,
   fnv1a_wrap_stream,
   fnv1a_checksum_finalize): FNV checksum creating stream wrapper
  (rep_write_baton,
   rep_write_get_baton,
   rep_write_contents_close): calculate FNV checksum for text reps
                              and store that in the p2p index
  (write_hash_rep,
   write_hash_delta_rep): ditto for properties & directories
  (write_final_rev): same for noderevs
  (write_final_changed_path_info): and for changed paths lists

* subversion/libsvn_fs_fs/pack.c
  (auto_pad_block): as per definition, empty sections use checksum 0


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/log-addressing@1516332 13f79535-47bb-0310-9956-ffa450edef68