[clang] [Clang][AMDGPU] Add builtins for some buffer resource atomics (PR #149216)

[via cfe-commits]

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+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
+// RUN: %clang_cc1 -triple amdgcn-unknown-unknown -target-feature +atomic-fmin-fmax-global-f32 -target-feature +atomic-fmin-fmax-global-f64 -emit-llvm -o - %s | FileCheck %s
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zGoldthorpe wrote:

These features don't seem to be enabled automatically by any target cpus.

https://github.com/llvm/llvm-project/pull/149216