[llvm] [BOLT] BB can be cold, warm and hot. (PR #121475)

[Paschalis Mpeis via llvm-commits]

paschalis-mpeis wrote:

Indeed, I remember seeing this assert in some instances when using `--split-strategy=cdsort` or `--split-strategy=all` on AArch64, but probably it also exists on other targets.

However, this would require more changes and verifying whether the prior logic is still sound. For example:
- the `setIsCold` (and it's users) is also not aware of 'warm' blocks.
- LongJmp is using it for creating/caching stubs and finding the hot/cold frontier
- sizes estimation in BinaryFunction
- a few more passes and metrics might also be incompatible

https://github.com/llvm/llvm-project/pull/121475