[libc] [llvm] [libc][math] Refactor exp2f16 implementation to header-only in src/__support/math folder. (PR #161993)

[Muhammad Bassiouni via llvm-commits]

bassiounix wrote:

### Merge activity

* **Oct 11, 8:25 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/161993).


https://github.com/llvm/llvm-project/pull/161993