dinput: Add missing definition to public header.
diff --git a/include/dinput.h b/include/dinput.h
index e8c5658..eee1fbd 100644
--- a/include/dinput.h
+++ b/include/dinput.h
@@ -114,6 +114,8 @@
 DECL_WINELIB_TYPE_AW(LPDIRECTINPUT2)
 #define IID_IDirectInput7 WINELIB_NAME_AW(IID_IDirectInput7)
 DECL_WINELIB_TYPE_AW(LPDIRECTINPUT7)
+#define IID_IDirectInput8 WINELIB_NAME_AW(IID_IDirectInput8)
+DECL_WINELIB_TYPE_AW(LPDIRECTINPUT8)
 #define IID_IDirectInputDevice WINELIB_NAME_AW(IID_IDirectInputDevice)
 DECL_WINELIB_TYPE_AW(LPDIRECTINPUTDEVICE)
 #define IID_IDirectInputDevice2 WINELIB_NAME_AW(IID_IDirectInputDevice2)