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

[Tomas Matheson via cfe-commits]

tmatheson-arm wrote:

Fixed SSBS and CCIDX.

> Does this also fix the "+nossbs" issue we saw earlier this week?

Yes, added a test https://github.com/llvm/llvm-project/pull/104435/files#diff-e355e3951d191d3a32265d9bdeb101e4f49ddfa6049ef058cf9e1dfdf7c19ef3

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