Slightly reduce the memory usage when writing to and reading from
changed path lists caches.  Since APR arrays are glorified memory
buffers with their structure being part of the ABI, we can read
and write them directly.

* subversion/libsvn_fs_fs/temp_serializer.c
  (svn_fs_fs__serialize_changes): Directly serialize from the
                                  array's data buffer.
  (svn_fs_fs__deserialize_changes): Use the copy already handed into
                                    this function as the array's buffer.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1605188 13f79535-47bb-0310-9956-ffa450edef68