[clang] [llvm] [clang] Reland Add tanf16 builtin and support for tan constrained intrinsic (PR #94559)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Yes, I think it's just a historical mistake; sin/cos/log/exp were added a very long time ago, and we weren't as careful about that sort of thing.  And nobody has taken the time to try to cleanup the current defaults.

https://github.com/llvm/llvm-project/pull/94559