dsound: Remove the useless CINTERFACE definition.
diff --git a/dlls/dsound/duplex.c b/dlls/dsound/duplex.c
index dbe811b..4a1fbd2 100644
--- a/dlls/dsound/duplex.c
+++ b/dlls/dsound/duplex.c
@@ -24,7 +24,6 @@
 
 #define NONAMELESSSTRUCT
 #define NONAMELESSUNION
-#define CINTERFACE
 #define COBJMACROS
 #include "windef.h"
 #include "winbase.h"