This effectively moves "null_event_cond" from struct d3d12_fence and
"latch" from struct vkd3d_waiting_event together into a separate
structure, as well as storing the signalling function in struct
vkd3d_waiting_event instead of getting it from struct d3d12_device. I
think that largely makes sense on its own, but storing the signalling
function in struct vkd3d_waiting_event also allows us to more easily
implement d3d12_device_SetEventOnMultipleFenceCompletion() in a
subsequent commit.
Currently structured TGSM loads are encoded to something like this:
ld_structured sr12 <s:float>, sr1 <s:uint>, l(0) <s:uint>, g0[sr1 <s:uint> + 0] <s:float>
Notice how the TGSM offset, expressed by sr1, is encoded twice in
the instruction. In TPF there is no expectation of two indices
in the resource source, so let's avoid producing it for DXIL as
well. The same instruction will therefore become:
ld_structured sr12 <s:float>, sr1 <s:uint>, l(0) <s:uint>, g0 <s:float>
Rather than an array of pointers to registers. This makes it nicer
to use with registers that are synthesized on the fly, a situation
that already exists and is likely to become more common in future
commits.
