[clang] [FMV][AArch64] Don't optimize backward compatible features in resolver. (PR #90928)

[Tomas Matheson via cfe-commits]

tmatheson-arm wrote:

I agree with the other comments, and also I think changes like this should not go in this fast and with so few eyes on them.

https://github.com/llvm/llvm-project/pull/90928