[clang] [llvm] [FMV][AArch64] Allow user to override version priority. (PR #150267)

[Peter Waller via cfe-commits]

https://github.com/peterwaller-arm approved this pull request.

The approach seems reasonable to me. I spent a bit of time looking over this and couldn't find anything significant. Since it is a big change please give a couple of days for any remaining comments to come in.

https://github.com/llvm/llvm-project/pull/150267