[PATCH vkd3d v4 7/7] vkd3d-shader/hlsl: Parse matrix constructors.

[Zebediah Figura]

Unfortunately this generates a couple of compilation warnings:

../vkd3d/libs/vkd3d-shader/hlsl.y: In function ‘add_constructor’:
../vkd3d/libs/vkd3d-shader/hlsl.y:2040:22: warning: unused variable 
‘width’ [-Wunused-variable]
  2040 |         unsigned int width;
       |                      ^~~~~
../vkd3d/libs/vkd3d-shader/hlsl.y:2028:21: warning: unused variable ‘j’ 
[-Wunused-variable]
  2028 |     unsigned int i, j, idx = 0;
       |                     ^