[clang] [llvm] [HLSL][DirectX] Emit convergence control tokens when targeting DirectX (PR #188792)

[Finn Plummer via cfe-commits]

inbelic wrote:

@Keenuts I will merge this tmrw after I confirm the hlsl test suite is passing as expected. Let me know if I should hold until you get a chance to review. Thanks

https://github.com/llvm/llvm-project/pull/188792