Fix gcc 4.0 -Wpointer-sign warnings.

diff --git a/dlls/ole32/hglobalstream.c b/dlls/ole32/hglobalstream.c
index 9895df6..ca73a22 100644
--- a/dlls/ole32/hglobalstream.c
+++ b/dlls/ole32/hglobalstream.c
@@ -60,7 +60,7 @@
   /*
    * Reference count
    */
-  ULONG		     ref;
+  LONG		     ref;
 
   /*
    * Support for the stream