[clang] [compiler-rt] [llvm] [FMV][AArch64] Unify ls64, ls64_v and ls64_accdata. (PR #108024)

[Alexandros Lamprineas via cfe-commits]

labrinea wrote:

Just letting you know that I have reopened https://github.com/llvm/llvm-project/pull/101712 as a draft just to demonstrate that backwards compatibility can be preserved if we split the features (previously I thought it wasn't possible, but I found a way). However I couldn't convince people to revert the ACLE patch https://github.com/ARM-software/acle/pull/346 therefore I will be merging this patch by the end of today if there are no objections. Many thanks to everyone involved in the reviews!

https://github.com/llvm/llvm-project/pull/108024