[clang] [libc] [RFC][clang][libc] Extend the ext_vector_type attribute to support the scalable vector sizes (PR #183307)

[Paul Osmialowski via cfe-commits]

pawosm-arm wrote:

> it's not perfect (an assertion is failing on one of the clang tests, and there are some formatting complaints)

Turned out I've forgotten to add SVE-guarding condition, so it always been trying to build scalable types even on X86.


https://github.com/llvm/llvm-project/pull/183307