[llvm] [BasicBlockSections] Using MBBSectionID as DenseMap key (PR #97295)

[Haohai Wen via llvm-commits]

HaohaiWen wrote:

> Sorry, I was OOO and didn't get a chance to look at this. You mention that `A Cold type MBBSectionID with number 0 and a Default type MBBSectionID with number 2 get same value 2 from getSectionIDNum`, but I think the former will get 0 and the will get 2. Am I missing anything?

Oh sorry. It's typo...
```
It should be
A Cold type MBBSectionID with number 2 and a Default type MBBSectionID with number 0 get same value 2 from getSectionIDNum
```

https://github.com/llvm/llvm-project/pull/97295