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

[via llvm-commits]

pcc wrote:

Yes, technically the program does continue but my point is that won't matter to the user because the output file will not be generated if the program is implemented correctly. By "ignore all errors" flag I mean something like the `--noinhibit-exec` passed to lld, which would convert errors to warnings where possible. I'm not sure if this error would actually be converted to a warning by that flag, though.

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