[Bug 42740] Icons with transparency no longer rendering correctly

https://bugs.winehq.org/show_bug.cgi?id=42740

--- Comment #2 from Johannes  ---
I am actually the OpenMPT developer who implemented this work-around.

The work-around we utilize for Wine is also used on other systems which do not
support 32-bit images with alpha channel, e.g. when using a 24-bit graphics
mode.
What Wine 2.4 does is neither consistent with Windows in 32-bit mode, nor with
Windows in 16-bit or 24-bit mode. In the latter case (which is applied for
Wine), the 8-bit alpha is pre-calculated and reduced to a 1-bit mask and the
image is loaded with ILC_COLOR24 | ILC_MASK. However, Wine now ignores this
1-bit mask completely, which it previously did not.