layers: Add minimal actual analysis of interface blocks to DrawState

There's definitely still room for improvement here (SPIRV-Tools might have some stuff that will make some of these more complex module walks a little clearer); however, this adds enough support for interface blocks for us to generate all the same kinds of mismatch errors we were previously generating for loose inputs and outputs.

Signed-off-by: Chris Forbes <chrisforbes@google.com>
2 files changed