d3d8/tests: Only run the vertex/pixel shader constant apply tests when the implementation supports them.

widl: Allow pointers, type-qualifiers and other more complicated constructions in sizeof and cast expressions.

Make it return the var_t object rather than making the callers dig it
out, and make it take the attributes list so that callers don't have
to set it.

The range will not be verified in and misconception could turn into a
security problem.

Move [string] attribute validation from reg_typedefs to set_type.