Haven't been using these for a while.
I've come to the conclusion here that I think it's better to try to
deal with the issues using safe workarounds like copies, instead of
relying on features with somewhat iffy driver support that are not
universal across APIs anyway.
Slightly reduces the number of unique vertex shaders but doesn't do much
for the pipeline count, as the fragment shader has a tex flag. Still
worth doing for the simplification.
In #16104, we drastically reduced the number of shader variants for
games that use flexible lighting setups. I looked at a few games and it
seems that a lot of games have the same shaders with fog on/off, while
fog is super cheap to compute. So let's just always do it, reducing
vertex shader variants further (though the amount of pipelines will probably
remain the same, since we still specialize the fragment shader).
Might also be worth adding a dynamic bool for the fragment shader, but
if so, doing it separately.
Ran into this with cache files from previous version of my change.
Also bumping the shader cache ID again to avoid this in other ways, but
good to be robust here.
