vkd3d-shader/hlsl: Handle register(cX) reservations.
Currently we are not properly handling register(cX) reservations for SM1, this is one of the things required for the SNK shaders (CW Bug Bug 18092).
register(cX) reservations also change the offset in the $Globals buffer in SM4, so support for this is also included.
Patch 1/4 is required to specify:
[require]
shader model < 4.0
so that the tests that follow do not get run with the vulkan backend on SM4. I think nobody disagreed with that patch.