d3dx9: Add d3dx9effect.h include file.
diff --git a/include/d3dx9.h b/include/d3dx9.h
index 47d2830..ccf731e 100644
--- a/include/d3dx9.h
+++ b/include/d3dx9.h
@@ -32,6 +32,7 @@
 #include "d3dx9core.h"
 #include "d3dx9mesh.h"
 #include "d3dx9shader.h"
+#include "d3dx9effect.h"
 #include "d3dx9tex.h"
 
 #define _FACDD 0x876