Merge r1636874 from trunk:

 * r1636874
   Provide @since information in svn_stream_skip docstring.
   Justification:
     Our API docs should be accurate.
   Votes:
     +1: stefan2, julianfoad


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x@1640478 13f79535-47bb-0310-9956-ffa450edef68