* subversion/include/private/svn_ra_svn_private.h,
  subversion/libsvn_ra_svn/marshal.c
  (svn_ra_svn__write_cmd_failure): Document that the 'err' input parameter
    is not cleared, and make it 'const' to reinforce this.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1584610 13f79535-47bb-0310-9956-ffa450edef68