Recovery of release 990110 after disk crash.
See Changelog for changes between 990103 and 990110.

diff --git a/include/dplay.h b/include/dplay.h
index fd9552e..d6d5506 100644
--- a/include/dplay.h
+++ b/include/dplay.h
@@ -2,6 +2,8 @@
 #ifndef __WINE_DPLAY_H
 #define __WINE_DPLAY_H
 
+#include "unknwn.h"
+
 #pragma pack(1)
 
 /* Return Values for Direct Play */