[llvm] [DevPolicy] Add guidance to not submit code or reviews on someone else's (PR #69701)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

I don't think wording of the change makes sense; it doesn't make sense without the context of the announcement.  It doesn't really explain why people should be suspicious of such requests, or why we don't want people to accept such requests.  If we're specifically concerned about ban-evasion, we should say that explicitly, I think.

Maybe also more explicitly distinguish between creating a PR on behalf of someone else (which shouldn't be happening), vs. creating a PR that happens to contain code authored by someone else (which is generally not suspicious).

https://github.com/llvm/llvm-project/pull/69701