[llvm] [X86] Added sincos vector lib codegen test coverage (PR #183702)

[Aadarsh Keshri via llvm-commits]

Aadarsh-Keshri wrote:

> how bulky does this get if you add libmvec coverage as well?

Nothing much changed; Only the note at the end changed.

`CHANGE` parameter in `--check-prefixes` reduced generated asserted significantly.

https://github.com/llvm/llvm-project/pull/183702