On the log-addressing branch:  Use the phys-to-log index to verify
the pack / rev file contents (size and checksum).

* subversion/libsvn_fs_fs/verify.c
  (STREAM_THRESHOLD): define yet anther block size
  (expect_buffer_nul,
   read_all_nul,
   expected_checksum,
   expected_buffered_checksum,
   expected_streamed_checksum,
   compare_p2l_to_rev): implement checksum verification
  (verify_index_consistency): call the new verification function

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/log-addressing@1516336 13f79535-47bb-0310-9956-ffa450edef68