[clang] [CIR] Upstream AtomicFenceOp and signal/thread fence builtins (PR #168346)

[Bruno Cardoso Lopes via cfe-commits]

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@@ -4845,4 +4845,39 @@ def CIR_AtomicClearOp : CIR_Op<"atomic.clear"> {
   }];
 }
 
+def CIR_MemScopeKind : CIR_I32EnumAttr<"MemScopeKind", "memory scope kind", [
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bcardosolopes wrote:

Seems like you are referring to an old version of incubator, we use `CIR_SyncScopeKind` there, please make sure this PR reflects the most updated version here and elsewhere in the PR.

https://github.com/llvm/llvm-project/pull/168346