fix #68882, cleanup the XInclude copying of node, merge back IDs in the

* tree.c valid.c xinclude.c: fix #68882, cleanup the XInclude
  copying of node, merge back IDs in the target document.
* result/XInclude/docids.xml test/XInclude/docs/docids.xml
  test/XInclude/ents/ids.xml: test case
* result/VC/ElementValid4: output changed due to a typo fix
Daniel
8 files changed