fix the key initialization problem introduced when tracking Josef Urban

fix the key initialization problem introduced when tracking Josef Urban

* libxslt/documents.c libxslt/keys.c libxslt/xsltInternals.h
  libxslt/transform.c libxslt/pattern.c: fix the key initialization
  problem introduced when tracking Josef Urban problem from 22 Dec
  2007, this should also handle the problem of recursive keys
  definitions should fix #531873.
* tests/docs/bug-166.xml tests/docs/Makefile.am
  tests/general/Makefile.am tests/general/bug-166.xsl
  tests/general/bug-166.out: add the regression tests when a key
  computation depends on another one.
Daniel

svn path=/trunk/; revision=1471