[llvm] [LV] Add initial support for vectorizing literal struct return values (PR #109833)

[Sander de Smalen via llvm-commits]

sdesmalen-arm wrote:

> Oh I didn't know that, I thought we didn't support vectorizing loops with sincos previously?

It did when there was a vector function mapping for it, @MacDue disabled this in #108980.

https://github.com/llvm/llvm-project/pull/109833