microsoft/compiler: Satisfy DXIL validator around gvar linkage
Not sure why this isn't broken for you guys, but I'm hitting validation that breaks all the "local" variable tests: https://github.com/microsoft/DirectXShaderCompiler/blob/d3af7f1237c1bafd130dfb79062e978f51007712/lib/IR/Verifier.cpp#L465.
/cc @bbrezillon @daniels