gdiplus: Add stub for GdipImageRotateFlip.

include/gdiplusflat.h

diff --git a/include/gdiplusflat.h b/include/gdiplusflat.h
index 3cc6d26..a7ee536 100644
--- a/include/gdiplusflat.h
+++ b/include/gdiplusflat.h
@@ -340,6 +340,7 @@
 GpStatus WINGDIPAPI GdipImageGetFrameCount(GpImage*,GDIPCONST GUID*,UINT*);
 GpStatus WINGDIPAPI GdipImageGetFrameDimensionsCount(GpImage*,UINT*);
 GpStatus WINGDIPAPI GdipImageGetFrameDimensionsList(GpImage*,GUID*,UINT);
+GpStatus WINGDIPAPI GdipImageRotateFlip(GpImage*,RotateFlipType);
 GpStatus WINGDIPAPI GdipImageSelectActiveFrame(GpImage*,GDIPCONST GUID*,UINT);
 GpStatus WINGDIPAPI GdipLoadImageFromFile(GDIPCONST WCHAR*,GpImage**);
 GpStatus WINGDIPAPI GdipLoadImageFromFileICM(GDIPCONST WCHAR*,GpImage**);