StretchBlt halftone mode doesn't work correctly

On 20210215-0.4.15-dev-2056-g8b6e5e8.GNU_8.4.0:

The StretchBlt function with setting STRETCH_HALFTONE mode by using SetStretchBltMode function doesn't work correctly.

1. Extract HalftoneStretchBlt.zip.
2. Execute HalftoneStretchBlt.exe in HalftoneStretchBlt folder.
3. File output.bmp will be generated.
4. The pixels must be RGB(64, 64, 64) in Windows, but RGB(0, 0, 0) in ReactOS.

Generally, STRETCH_HALFTONE mode is used for smoothly stretching bitmap image.