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

[Nathan Gauër via llvm-commits]

Keenuts wrote:

> Irrelevant to this PR, but nevertheless -- this `CodeGen/SPIRV/debug-info/debug-type-basic.ll` recently started to fail in Github Actions and I'm not able to reproduce spirv-val complaint locally. Did you manage to reproduce that test case fail locally?

Same here, can see it's not related to this PR, but cannot reproduce it on my machine. Not sure why.

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