Teach spv-to-shaderdb-test.py to propagate XFAIL and REQUIRES constraints
Teach spv-to-shaderdb-test.py to propagate XFAIL and REQUIRES constraints

This should simplify adding new shaderdb tests without having to lookup
LIT documentation and LLPC local lit settings.

GPUOpen-Drivers/llpc,googlestadia/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,googlestadia/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc