Support BGR subpixel layout on Windows

[dimhatz]

First of all, thank you for this nice library and the alacritty terminal that uses it.

This issue is for alacritty, but I think the appropriate place for it is here.

On windows, when using a BGR monitor / TV, the font rendering is very ugly (with noticeable color fringes).
On linux, this was fixed, according to alacritty/alacritty#4100 (AFAICT the fix was implemented in this library).

Adding some reference info, on how to detect which subpixel layout is used on Windows (in case it may be useful):

Microsoft docs

Investigation by BetterClearTypeTuner (2019)

Thank you again for your good work!