[libclc] [libclc] update __clc_mem_fence: add MemorySemantic arg and use __builtin_amdgcn_fence for AMDGPU (PR #152275)

[Wenju He via cfe-commits]

wenju-he wrote:

kindly ping @arsenm @frasercrmck to review the last commit. It is a renaming commit.

https://github.com/llvm/llvm-project/pull/152275