[clang] [llvm] [clang] Add tanf16 builtin and support for tan constrained intrinsic (PR #93314)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

@ilovepi,  How many platforms do you build Fuchsia for? It will be important to know which backends needs support before we try to re-land this. 

https://github.com/llvm/llvm-project/pull/93314