Make `svn --version -v` identify OS X 10.9 as Mavericks.

* subversion/libsvn_subr/sysinfo.c
  (release_name_from_version): Add case for minor 9.  Yay for manually
    maintained lists.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1573088 13f79535-47bb-0310-9956-ffa450edef68