[clang] [llvm] [RISCV] Add support for getHostCPUFeatures using hwprobe (PR #94352)

[Pengcheng Wang via cfe-commits]

wangpc-pp wrote:

> I have no idea about why it corrupts StringMap. Sad :(
> 
> ![image](https://private-user-images.githubusercontent.com/15650457/341986439-fd427068-6ca0-4ecb-a340-48c51e5629a6.png?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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.z46AIxQBdVWJ2Z6xGXCA_5v54-NU9KwydxMTUHXxuRo)

Is this fixed after fixing the return statement? This may be caused by the corruption of `getHostCPUNameForRISCV`.

https://github.com/llvm/llvm-project/pull/94352