[clang] [flang] [llvm] Initial support for vectorization using HVML (Hygon vector math library) (PR #219098)

[Xiaomeng Zhang via cfe-commits]

JacketPants wrote:

> Please split up the PR into incremental changes: there are at least 3 separate changes: 1) llvm support for the new lib, 2) clang support, 3) flang support

@fhahn I've split this into three PRs:

1. LLVM support for the new library — #222632
2. Clang support — will follow in a separate PR built on top of #222638
3. Flang support — will follow in a separate PR built on top of #222639

https://github.com/llvm/llvm-project/pull/219098