removed the error message removed 2 instability warnings from function

* runtest.c: removed the error message
* relaxng.c xmlschemas.c: removed 2 instability warnings from function
  documentation
* include/libxml/schemasInternals.h: changed warning about API stability
* xmlregexp.c: trying to improve runtime execution of non-deterministic
  regexps and automata. Not fully finished but should be way better.
Daniel
diff --git a/runtest.c b/runtest.c
index 897cb9b..dff53c3 100644
--- a/runtest.c
+++ b/runtest.c
@@ -2926,14 +2926,13 @@
     unlink(temp);
     free(temp);
 
-    if (err != NULL) {
+    if ((ret != 0) && (err != NULL)) {
 	if (compareFileMem(err, testErrors, testErrorsSize)) {
 	    fprintf(stderr, "Error for %s on %s failed\n", filename, sch);
 	    ret = 1;
 	}
     }
 
-
     xmlSchemaFreeValidCtxt(ctxt);
     xmlFreeDoc(doc);
     return(ret);