[compiler-rt] [clang-tools-extra] [clang] [llvm] [flang] [bpi] Reuse the AsmWriter's BB naming scheme (PR #73593)

[Mircea Trofin via cfe-commits]

mtrofin wrote:

> I'm not an expert on branch-probability facilities, but the test changes look highly valuable,
> 
> It seems awkward to add an extra flag to the block-printer, as it introduces a number of conditionals -- would it be possible to refactor as a dedicated `printBlockName` method rather than an extra option for block printing?

I think @MatzeB's suggestion tackles this, ptal.

https://github.com/llvm/llvm-project/pull/73593