Added CN_* flags used in WM_COMMNOTIFY.

diff --git a/include/wine/winuser16.h b/include/wine/winuser16.h
index 1995448..827b17d 100644
--- a/include/wine/winuser16.h
+++ b/include/wine/winuser16.h
@@ -475,6 +475,11 @@
 
 #pragma pack(4)
 
+/* WM_COMMNOTIFY flags */
+#define CN_RECEIVE	0x0001
+#define CN_TRANSMIT	0x0002
+#define CN_EVENT	0x0004
+
 BOOL16      WINAPI CheckMenuRadioItem16(HMENU16,UINT16,UINT16,UINT16,UINT16);
 HICON16     WINAPI CopyImage16(HANDLE16,UINT16,INT16,INT16,UINT16);
 HICON16     WINAPI CreateIconFromResource16(LPBYTE,UINT16,BOOL16,DWORD);