[llvm] [OPT] Fixes print-changed=dot-cfg for unnamed basic blocks. (PR #148582)

[Shafik Yaghmour via llvm-commits]

shafik wrote:

It looks like there a fix here that has been reviewed: https://github.com/llvm/llvm-project/pull/148844 

I would like to have some feedback on if some elements from this one should be taken or vice verse.

@jamieschmeiser 

https://github.com/llvm/llvm-project/pull/148582