kmdb should panic when it can't allocate during setup
If kmdb can't allocate memory while setting itself up, it allocates again KM_SLEEP
The comment claims we'll hang, but of course we won't, because at that point we're single threaded and the dispatcher hasn't been set up. We'll panic, but we'll do so in a way far more confusing than if that cmn_err had actually just panicked in the first place.
You may think to yourself "But surely kmdb then won't work?" That might be true, but the current way panics anyway, just really annoyingly, and kmdb worked sufficiently then to discover this.
kmdb should panic, and use a message that clearly says "Out of memory" or "allocation failed".