vkd3d-shader/hlsl: Write SM4 thread ID registers.

tests/hlsl-numthreads.shader_test

@@ -171,7 +171,7 @@ size (2, 2)
 1.0 1.0
 1.0 1.0
 
-[compute shader todo]
+[compute shader]
 /* Attributes are taken from the first function, and dropped from the second. */
 RWTexture2D<float> u;
 
@@ -185,7 +185,7 @@ void main(uint2 id : sv_dispatchthreadid)
 }
 
 [test]
-todo dispatch 1 1 1
+dispatch 1 1 1
 probe uav 0 (0, 0) r (2.0)
 probe uav 0 (0, 1) r (1.0)
 probe uav 0 (1, 0) r (2.0)