[llvm] [AMDGPU] Replace relaxed-buffer-oob-mode feature with module flag (PR #160922)

[Piotr Sobczak via llvm-commits]

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piotrAMD wrote:

Right, I didn't think about that. Would it make sense to extend include/llvm/Support/AMDGPUMetadata.h? I can't find anything more suitable, and adding a new header just for this is probably an overkill.

https://github.com/llvm/llvm-project/pull/160922