fix a few warning raised by gcc-4.1 and latests changes Daniel

* c14n.c encoding.c xmlschemas.c xpath.c xpointer.c: fix a few
  warning raised by gcc-4.1 and latests changes
Daniel
diff --git a/xmlschemas.c b/xmlschemas.c
index d8824de..2059196 100644
--- a/xmlschemas.c
+++ b/xmlschemas.c
@@ -2825,7 +2825,8 @@
     if (attr == NULL) {
 	xmlSchemaPErrExt(ctxt, NULL, error, NULL, NULL, NULL,
 	    "%s, attribute '%s': %s.\n",
-	    BAD_CAST des, "Unknown", (const xmlChar *) msg, NULL, NULL);
+	    BAD_CAST des, (const xmlChar *) "Unknown",
+	    (const xmlChar *) msg, NULL, NULL);
     } else {
 	xmlSchemaPErrExt(ctxt, (xmlNodePtr) attr, error, NULL, NULL, NULL,
 	    "%s, attribute '%s': %s.\n",
@@ -8000,7 +8001,7 @@
 	* field.
 	*/
 	if (attr == NULL)
-	    nsList == NULL;
+	    nsList = NULL;
 	else
 	    nsList = xmlGetNsList(attr->doc, attr->parent);
 	/*