applied patch to fix xmlListAppend() from Georges-André SILBER also fix

* list.c: applied patch to fix xmlListAppend() from 
  Georges-André SILBER
* valid.c: also fix the place wher it was called.
Daniel

svn path=/trunk/; revision=3614
diff --git a/list.c b/list.c
index 2dc6d96..5c01c83 100644
--- a/list.c
+++ b/list.c
@@ -314,14 +314,14 @@
     if (lkNew == NULL) {
         xmlGenericError(xmlGenericErrorContext, 
 		        "Cannot initialize memory for new link");
-        return (0);
+        return (1);
     }
     lkNew->data = data;
     lkNew->next = lkPlace->next;
     (lkPlace->next)->prev = lkNew;
     lkPlace->next = lkNew;
     lkNew->prev = lkPlace;
-    return 1;
+    return 0;
 }
 
 /**