[llvm] [AMDGPU] Add target feature for waits before system scope stores. NFC. (PR #164993)

[Matt Arsenault via llvm-commits]

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@@ -1466,6 +1466,12 @@ def FeatureClusters : SubtargetFeature< "clusters",
   "Has clusters of workgroups support"
 >;
 
+def FeatureWaitsBeforeSystemScopeStores
+    : SubtargetFeature<"waits-before-system-scope-stores",
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arsenm wrote:

I think we need to turn off clang-format for tablegen. I don't think I've ever seen it make a good suggestion 

https://github.com/llvm/llvm-project/pull/164993