On the log-addressing branch:  Normalize all FNV-1* checksum
representations to big endian that we already use in 
svn_checksum_t digests.

* subversion/include/svn_checksum.h
  (svn_checksum_kind_t): extend docstrings to describe what
                         we already do in svn_checksum_t

* subversion/include/private/svn_subr_private.h
  (svn__fnv1a_32,
   svn__fnv1a_32x4): update docstring, code needs to change

* subversion/libsvn_subr/fnv1a.c
  (finalize_fnv1a_32x4,
   svn__fnv1a_32,
   svn_fnv1a_32__finalize): return checksums in big endian

* subversion/libsvn_subr/checksum.c
  (svn_checksum,
   svn_checksum_final): simplify

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/log-addressing@1516315 13f79535-47bb-0310-9956-ffa450edef68