suppressed warnings from within xmlValidGetValidElements (bug 144644)

* valid.c: suppressed warnings from within xmlValidGetValidElements
  (bug 144644)
* doc/examples/testWriter.c: corrected typo in comment for ISO-8859-1
  (bug 144245)
diff --git a/valid.c b/valid.c
index e78d7be..18a1fde 100644
--- a/valid.c
+++ b/valid.c
@@ -6586,6 +6586,14 @@
    return(*len);
 }
 
+/*
+ * Dummy function to suppress messages while we try out valid elements
+ */
+static void xmlNoValidityErr(void *ctx ATTRIBUTE_UNUSED,
+                                const char *msg ATTRIBUTE_UNUSED, ...) {
+    return;
+}
+
 /**
  * xmlValidGetValidElements:
  * @prev:  an element to insert after
@@ -6631,14 +6639,15 @@
     
     xmlElement *element_desc;
 
-    memset(&vctxt, 0, sizeof (xmlValidCtxt));
-
     if (prev == NULL && next == NULL)
         return(-1);
 
     if (names == NULL) return(-1);
     if (max <= 0) return(-1);
 
+    memset(&vctxt, 0, sizeof (xmlValidCtxt));
+    vctxt.error = xmlNoValidityErr;	/* this suppresses err/warn output */
+
     nb_valid_elements = 0;
     ref_node = prev ? prev : next;
     parent = ref_node->parent;