[llvm] [StructurizeCFG] Fix a crash caused by not updating `Predicates` properly (PR #124051)

[Shilei Tian via llvm-commits]

shiltian wrote:

> Can you elaborate on how it's not correct?

It looks like the predicate was not constructed correctly at the first place but I don't understand some logic behind how it is constructed after spending several days on it, so I gave it up. After the change made in this PR, a lot of tests need to be updated. I checked some of them. They don't look like the right change.

> At minimum should commit the xfailed test

Sure, will do that.

https://github.com/llvm/llvm-project/pull/124051