Fix unability to validate ambiguously constructed interleave for RelaxNG

Previously, test/relaxng/ambig_name-class.xml would fail to validate
for a simple reason -- interleave within "open-name-class" context
is supposed to be fine with whatever else is pending the consumption,
since effectively, it's unrelated from a higher parsing perspective.
Signed-off-by: Jan Pokorný <jpokorny@redhat.com>

relaxng.c

@@ -9476,7 +9476,17 @@ xmlRelaxNGValidateInterleave(xmlRelaxNGValidCtxtPtr ctxt,
             xmlRelaxNGFreeValidState(ctxt, oldstate);
             oldstate = ctxt->state;
             ctxt->state = NULL;
-            if (cur != NULL) {
+            if (cur != NULL
+                    /* there's a nasty violation of context-free unambiguities,
+                       since in open-name-class context, interleave in the
+                       production shall finish without caring about anything
+                       else that is OK to follow in that case -- it would
+                       otherwise get marked as "extra content" and would
+                       hence fail the validation, hence this perhaps
+                       dirty attempt to rectify such a situation */
+                    && (define->parent->type != XML_RELAXNG_DEF
+                        || !xmlStrEqual(define->parent->name,
+                                        (const xmlChar *) "open-name-class"))) {
                 VALID_ERR2(XML_RELAXNG_ERR_INTEREXTRA, cur->name);
                 ret = -1;
                 ctxt->state = oldstate;

result/relaxng/ambig_name-class_err

+./test/relaxng/ambig_name-class.rng validates

test/relaxng/ambig_name-class.rng

+tutorA.rng
\ No newline at end of file

test/relaxng/ambig_name-class.xml

+<grammar xmlns="http://relaxng.org/ns/structure/1.0" >
+  <start>
+    <element name="foo">
+      <attribute>
+        <choice>
+          <name>alpha</name>
+          <name>bravo</name>
+        </choice>
+        <choice>
+          <value>none</value>
+          <value>all</value>
+        </choice>
+      </attribute>
+    </element>
+  </start>
+</grammar>