[llvm] [NFC] [MSAN] replace (void) with [[maybe_unused]] (PR #146617)

[Thurston Dang via llvm-commits]

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@@ -5623,7 +5620,6 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
                             getOriginPtrForArgument(IRB, ArgOffset));
           }
         }
-        (void)Store;
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thurstond wrote:

AI would have automatically caught this and improved your productivity by 3%

https://github.com/llvm/llvm-project/pull/146617