[PATCH vkd3d 1/5] vkd3d-shader: Write SM1 subtraction instructions.

[Matteo Bruni]

Signed-off-by: Matteo Bruni <mbruni at codeweavers.com>
---
Sorry for the delay, I totally missed this patch series...
/me updates his email filtering rules

We should probably get rid of HLSL_IR_BINOP_SUB at some point:
HLSL_IR_BINOP_ADD + HLSL_IR_UNOP_NEG does the same thing at least as
well and it's one less case to handle in a number of places. Also on
the output side, there is no corresponding SM4+ instruction and IIRC
the native compiler doesn't generate SUB instructions for SM1 either.