[llvm] [DirectX] Disable DCE and DSE for -O0 (PR #192520)

[Justin Bogner via llvm-commits]

bogner wrote:

I'm slightly concerned that there may be some surprisingly simple patterns with resources where doing this will cause us to not be able to forward accesses sufficiently to be able to lower resource accesses unambibuously. I'll try to come back with some examples (probably early next week) and come back to you on this.

https://github.com/llvm/llvm-project/pull/192520