[compiler-rt] [mlir] [llvm] [clang] [libcxx] [flang] [clang-tools-extra] [libc] Make SmallVectorImpl destructor protected (PR #71439)

[Jakub Kuderski via cfe-commits]

https://github.com/kuhar approved this pull request.

I think we have reached consensus that this is the preferred direction. `SerializeToHsaco` is a tiny detail in the grand scheme of things, and because this PR doesn't make it any worse, I don't think we should be blocked by it.

https://github.com/llvm/llvm-project/pull/71439