[llvm] [BOLT] Turn non-empty CFI StateStack assert into a warning (PR #102216)

[Rafael Auler via llvm-commits]

https://github.com/rafaelauler approved this pull request.

The opposite, popping more items than pushed, would be a real concern. Since this assertion checks whether the CFI stack is inconsistent because it pushed more items than popped, it should be OK to convert the assertion into a warning.

https://github.com/llvm/llvm-project/pull/102216