[clang] [clang] Resolve FIXME: Use HalfWidth and HalfAlign for shorts (PR #81367)

[Sergei Barannikov via cfe-commits]

s-barannikov wrote:

> Shorts are half an int, so HalfWidth and HalfAlign apply here.

This is not true for our downstream target where `short` has the same width as `int` (note that the standard allows it).
It would be better to introduce `ShortWidth` / `ShortAlign` fields and initialize them to 16 by default.


https://github.com/llvm/llvm-project/pull/81367