[clang] [llvm] [RISCV] Add NutShell RV32/64 processors definition (PR #102899)

[Yingwei Zheng via cfe-commits]

https://github.com/dtcxzyw requested changes to this pull request.

After consulting with NutShell's maintainer @poemonsense, I think this PR should be rejected for the following reasons:
1. There are no commercial plans for this educational processor.
2. This project is no longer maintained.


https://github.com/llvm/llvm-project/pull/102899