fixed an error from #120684 patch raised in #127450 added tests to the

* libxslt/keys.c: fixed an error from #120684 patch raised in
  #127450
* tests/docs/Makefile.am tests/docs/bug-134.xml
  tests/general/Makefile.am tests/docs/bug-134*: added tests
  to the regression suite for bug #127450.
Daniel