wined3d: Implement vertical refresh sync.
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index 49081b1..de38042 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -1404,6 +1404,7 @@
     WINED3DFORMAT             orig_fmt;
 
     long prev_time, frames;   /* Performance tracking */
+    unsigned int vSyncCounter;
 
     WineD3DContext        **context; /* Later a array for multithreading */
     unsigned int            num_contexts;