Properly passing the inverse-trig.shader_test tests whose qualifiers
have been removed requires making spirv.c capable of handling ABS.
The same happens for the ps_3_0 equality test in
float-comparison.shader_test.
At the current moment this is a little odd because for SM1 [test]
directives are skipped, and the [shader] directives are not executed by
the shader_runner_vulkan.c:compile_shader() but by the general
shader_runner.c:compile_shader(). So in principle it is a little weird
that we go through the vulkan runner.
But fret not, because in the future we plan to make the parser agnostic
to the language of the tests, so we will get rid of the general
shader_runner.c:compile_shader() function and instead call a
runner->compile_shader() function, defined for each runner. Granted,
most of these may call a generic implementation that uses native
compiler in Windows, and vkd3d-shader on Linux, but it would be more
conceptually correct.
