make the number of available font slots variable,
set up a "quirk" mechanism to tell the generic vga code about crippled
VGA adapters which ignore the "fontsel" TS register,
initiate the quirk table with an ATI chip which happened to be on a board
I tested with.
Afaik quite a number of ATI chips suffers from the "loaded fonts don't
work" problem - these should be added.
Bad side effect of my change: The builtin font will be kicked out
always if a VGA_CONSOLE_SCREENTYPE is specified which needs a loaded
font. In early console initialization, we don't know much about the
graphics card, so we have to assume the worst (ie ATI:-).