[llvm] [SPIR-V] Fix block sorting with irreducible CFG (PR #116996)

[Vyacheslav Levytskyy via llvm-commits]

VyacheslavLevytskyy wrote:

Does it make sense to add the reproducer from https://github.com/llvm/llvm-project/issues/116692, or those changes in the PR covers the reproducer's role in full?

https://github.com/llvm/llvm-project/pull/116996