[clang] [FMV][AArch64][clang] Emit fmv-features metadata in LLVM IR. (PR #118544)

[Andrew Carlotti via cfe-commits]

andrewcarlotti wrote:

> > Suppose you have target_version("i8mm+dotprod") and target_version("fcma").  The first version clearly has higher priority
> 
> According to the [current rules](https://arm-software.github.io/acle/main/acle.html#selection) yes, but IMO that rule is broken and doesn't match user expectation.

I chose my example (which @labrinea posted here) specifically so that it would still be valid after changing the priorities to use lexicographic ordering (for which I just created https://github.com/ARM-software/acle/pull/370). Your alternative example doesn't exhibit the issue that this patch is intended to address.

https://github.com/llvm/llvm-project/pull/118544