gdiplus: Add stub for GdipGetImageThumbnail.
diff --git a/include/gdiplusflat.h b/include/gdiplusflat.h
index 4041c2c..3cc6d26 100644
--- a/include/gdiplusflat.h
+++ b/include/gdiplusflat.h
@@ -328,6 +328,7 @@
GpStatus WINGDIPAPI GdipGetImageItemData(GpImage*,ImageItemData*);
GpStatus WINGDIPAPI GdipGetImagePixelFormat(GpImage*,PixelFormat*);
GpStatus WINGDIPAPI GdipGetImageRawFormat(GpImage*,GUID*);
+GpStatus WINGDIPAPI GdipGetImageThumbnail(GpImage*,UINT,UINT,GpImage**,GetThumbnailImageAbort,VOID*);
GpStatus WINGDIPAPI GdipGetImageType(GpImage*,ImageType*);
GpStatus WINGDIPAPI GdipGetImageVerticalResolution(GpImage*,REAL*);
GpStatus WINGDIPAPI GdipGetImageWidth(GpImage*,UINT*);