[clang] [llvm] [AArch64] Add a check for invalid default features (PR #104435)

[Sam Elliott via cfe-commits]

lenary wrote:

Just closing a loop because I didn't have the info until today: the Oryon info in this patch is correct, the core does have SSBS and CCIDX.

https://github.com/llvm/llvm-project/pull/104435