[clang] [compiler-rt] [llvm] [FMV][AArch64] Unify features memtag and memtag2. (PR #112511)

[Jon Roelofs via cfe-commits]

jroelofs wrote:

> However these instructions only work at Exception Level 1, so they would be unusable since FMV is a user space facility.

I don't understand this distinction: why is FMV seen as user-space only?

https://github.com/llvm/llvm-project/pull/112511