[llvm] Remove iOS 5 check for tailcalls on ARM (PR #133354)

[Jon Roelofs via llvm-commits]

jroelofs wrote:

A quick dig through the relevant radars suggests that the issue was lack of support in the _dynamic_ linker prior to iOS 5. This is the correct version check in that context. I think the proper fix for https://github.com/llvm/llvm-project/issues/102053 is to add a diagnostic in clang for this case.

https://github.com/llvm/llvm-project/pull/133354