Fix #8731: Always use a 32bpp blitter if font anti-aliasing is enabled. #8736
Motivation / Problem
OpenGL video drivers now sometimes cause an 8bpp blitter to be used. These can't do font anti-alias.
If any font should be anti-aliased, always use a 32bpp blitter.
Most video drivers result in a 32bpp anyway, so no real change for non-OpenGL video drivers.
Checklist for review
Some things are not automated, and forgotten often. This list is a reminder for the reviewers.