fixes a libtool problem on AMD 64bits builds found the validation problem

* libxml.spec.in: fixes a libtool problem on AMD 64bits builds
* relaxng.c: found the validation problem I had with interleave
  when not covering all remaining siblings
* Makefile.am test.relaxng/* result/relaxng/*: augmented the
  testsuite and check the RNG schemas against the RNG schemas
  given in appendix A
Daniel
diff --git a/result/relaxng/tutor7_1_3.err b/result/relaxng/tutor7_1_3.err
index 17a46f6..ac8d77a 100644
--- a/result/relaxng/tutor7_1_3.err
+++ b/result/relaxng/tutor7_1_3.err
@@ -1,3 +1,3 @@
-error detected at relaxng.c:4353
-error detected at relaxng.c:5255
-error detected at relaxng.c:5053
+error detected at relaxng.c:4385
+error detected at relaxng.c:5360
+error detected at relaxng.c:5143