[llvm] [mlir] [ADT] Make DenseMap/DenseSet more resilient agains OOM situations (PR #107251)

[Jakub Kuderski via llvm-commits]

kuhar wrote:

+1 to what @nikic said. As an ADT contributor, the thing I really value about our implementation is that it's much simpler than alternative hash maps that have to worry about exceptions. I think it's safe to say that LLVM developers at large are not used to / trained to think about exception safety, and this puts burden on subsequent contributors who may not care about handling these specific OOM conditions.

https://github.com/llvm/llvm-project/pull/107251