[llvm] CodeGenPrepare: Remove threadlocal_address intrinsic when cheap to recompute. (PR #87844)

[Matthias Braun via llvm-commits]

MatzeB wrote:

I also submitted #87841 to verify the assumption that arg0 of `threadlocal.address` is a thread-local `GlobalVariable`. (Turns out it currently fails 1 test, but it's debatable whether the test is okay).

https://github.com/llvm/llvm-project/pull/87844