further fixes for out of memory condition, mostly from Olivier Andrieu.

* SAX2.c, tree.c, uri.c, xmlIO.c, xmlreader.c: further
  fixes for out of memory condition, mostly from Olivier
  Andrieu.
* testOOM.c: some further improvement by Olivier, with
  a further small enhancement for easier debugging.
diff --git a/xmlIO.c b/xmlIO.c
index a51bf64..56d83c1 100644
--- a/xmlIO.c
+++ b/xmlIO.c
@@ -2180,6 +2180,9 @@
 	}
 #endif
     }
+    else
+      xmlInputCallbackTable[i].closecallback (context);
+
     return(ret);
 }