add stubs for XGL_WSI_X11
diff --git a/loader/loader.h b/loader/loader.h
index ca3f04e..b76f634 100644
--- a/loader/loader.h
+++ b/loader/loader.h
@@ -30,6 +30,7 @@
 
 #include <xgl.h>
 #include <xglDbg.h>
+#include <xglWsiX11Ext.h>
 
 #if defined(__GNUC__) && __GNUC__ >= 4
 #  define LOADER_EXPORT __attribute__((visibility("default")))