Removed some unnecessary inclusions of gdi.h.

diff --git a/dlls/x11drv/clipboard.c b/dlls/x11drv/clipboard.c
index 55dbb5c..9a14389 100644
--- a/dlls/x11drv/clipboard.c
+++ b/dlls/x11drv/clipboard.c
@@ -77,6 +77,7 @@
 #include "windef.h"
 #include "winbase.h"
 #include "winreg.h"
+#include "wine/wingdi16.h"
 #include "win.h"
 #include "x11drv.h"
 #include "wine/debug.h"