applied last patch for #110023 from Mark Vakoc fixed a memory leak when

* libexslt/strings.c: applied last patch for #110023 from
  Mark Vakoc
* libexslt/sets.c: fixed a memory leak when mixing one of the
  EXSLT set functions and a Result Value Tree
* TODO: there are other bugs around in libexslt/sets.c in conjunction
  with Result Value Tree
Daniel