[llvm] [llvm] Make target triple in TLII const reference (PR #127718)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

> This avoids making a copy whenever the function is being called with an argument coming from const& values returned from TM

The change itself makes sense, but the PR description leaves me confused. Passing a Foo& to const Foo& should produce a compiler error, not an implicit copy, right?

https://github.com/llvm/llvm-project/pull/127718