libxslt

* libxslt/transform.c: closing #94933, any error will make
  the transformation abort with  no result.
* tests/reports/tst-1.err tests/reports/tst-1.out
  tests/reports/undefvar.err: this changed the regression tests
  output.
* tests/exslt/date/difference.1.out tests/exslt/date/seconds.1.out:
  updated the result accordingly to the fixes done last month.
* libxslt/namespaces.c: make sure to avoid duplicate namespace
  declarations in the result trees. May fix #93692 but it's unclear.
Daniel