Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=56162
Storing to a vector component using a non-constant index is not allowed
on profiles lower than 6.0. Unless this happens inside a loop that can be
unrolled, which we are not doing yet.
For this reason, a validate_nonconstant_vector_store_derefs pass is
added to detect these cases.
Ideally we would want to emit an hlsl_error on this pass, but before
implementing loop unrolling, we could reach this point on valid HLSL.
Also, as pointed out by Nikolay in the mentioned bug, currently
new_offset_from_path_index() fails an assertion when this happens,
because it expects an hlsl_ir_constant, so a check is added.
It also felt correct to emit an hlsl_fixme there, despite the
redundancy.
The location of dxcompiler should be set during configuration with
'DXCOMPILER_LIBS=-L/path/to/dxcompiler', and then at runtime with
LD_LIBRARY_PATH, WINEPATH or PATH as applicable.
A new 'fail(sm<6)' decoration is needed on many shader declarations
because dxcompiler succeeds on many shaders which fail with fxc. The
opposite case is less common and is flagged with 'fail(sm>=6)'. A few
tests cause dxcompiler to crash or hang, so these are avoided using
[require], which now skips tests until reset instead of exiting. Also,
'todo(sm<6)' and 'todo(sm>=6)' are used to separate checking of results.
