/usr/i686-w64-mingw32/include/gdiplus/ is in mingw-w64-i686-dev 3.2.0-2.
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/usr/i686-w64-mingw32/include/gdiplus/gdiplus.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusbase.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusbrush.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluscolor.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluscolormatrix.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluseffects.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusenums.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusflat.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusgpstubs.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusgraphics.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusheaders.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusimageattributes.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusimagecodec.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusimaging.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusimpl.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusinit.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluslinecaps.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusmatrix.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusmem.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusmetafile.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusmetaheader.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluspath.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluspen.h
/usr/i686-w64-mingw32/include/gdiplus/gdipluspixelformats.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplusstringformat.h
/usr/i686-w64-mingw32/include/gdiplus/gdiplustypes.h