[llvm] [profcheck] Require `unknown` metadata have an origin parameter (PR #157594)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

What's the main purpose of doing this? This doesn't seem super relevant to the profcheck stuff, because that's catching places where the metadata was just completely ignored.

This also adds a bit of overhead (presumably only in an asserts build when profcheck is enabled) when this data could be obtained by bisecting the pass pipeline/in a debugger, although both of those are much less convenient.

https://github.com/llvm/llvm-project/pull/157594