[NativeAOT-LLVM] Work around poor inlined `memset` code quality in LLVM#3183

jkotas merged 2 commits intodotnet:feature/NativeAOT-LLVMdotnet/runtimelab:feature/NativeAOT-LLVMfrom

SingleAccretion:MemCpyWorkAroundSingleAccretion/runtimelab:MemCpyWorkAroundCopy head branch name to clipboard