Finally I took some time to look at the package and decided not to add it for the following reasons:
function CreateBitmapMask:
First, creating a mask is already part of TRasterImage.
Second, some implementations are empty
function DirectMaskBlt:
Comment says it all, this is a stripped version of LCL.StretchMaskBlt
I see no reason to add duplicate code.
function OptimalPixelFormat:
This always should be pfDevice, if not then there is something else wrong.
function OSSupportsUTF16:
this is an OS function not a widgetset function, so it doesn't belong here
This flag shouldn't be needed anyway, the LCL is always utf8, when dealing with OS functions, use the proper SysXXX conversion routines