windisplay: Undefine Configure before including d3d9.h

This is for consistency with fbbc5bb9e63 which introduced the
same `#undef Configure` in dxgsg9. This prevents dtool's own
Configure() macro from conflicting with the declaration of
D3D9's Configure function in d3d9.h.

panda/src/windisplay/winDetectDx9.cxx

@@ -18,6 +18,7 @@
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN 1
 #endif
+#undef Configure
 #include <d3d9.h>
 #include "graphicsStateGuardian.h"
 #include "graphicsPipe.h"