[llvm] DAG: Consider __sincos_stret when deciding to form fsincos (PR #165169)

[Benjamin Maxwell via llvm-commits]

https://github.com/MacDue commented:

This seems reasonable. Are you planning on doing anything for AArch64 (which has a similar pattern, but falls back to `Expand`)?

https://github.com/llvm/llvm-project/pull/165169