[llvm] [NewPM][BPF] Add `BPFCodeGenPassBuilder` (PR #94158)

[Yingchi Long via llvm-commits]

https://github.com/inclyc commented:

Just a nit picking.

Is this an adoption to refactored NewPM pass builder?

https://github.com/llvm/llvm-project/pull/89708

https://github.com/llvm/llvm-project/pull/94158