[llvm] Fix error message when regalloc eviction advisor analysis could not be created (PR #72165)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> Maybe also remove the words "Using default"? It's an error, the compiler isn't going to "use" anything.

It's an error, but not an error that causes an exit, as the state is still fine to continue on from. The variable comes from https://github.com/hiraditya/llvm-project/blob/0175a1e4d33720ed7e827b3db5a36f88bdd790a3/llvm/lib/CodeGen/RegAllocEvictionAdvisor.cpp#L93. If the user requests an ML analysis and it can't be created (eg due to the user not building with the ML stuff enabled), `NotAsRequested` is set to true, and the default advisor is constructed. Everything still works with the default advisor, it's just not what the user requested.

https://github.com/llvm/llvm-project/pull/72165