added additional check to prevent superfluous namespace href's being

* libxslt/namespaces.c: added additional check to prevent
  superfluous namespace href's being generated on elements
  (bug 136914)
* tests/namespaces/Makefile.am, tests/namespaces/tst5.x[ms]l:
  added new test for bug 136914
* tests/namespaces, tests/extensions/ tests/reports: fixed
  error in "enhanced" Makefile.am, removed superfluous .err files
  from cvs