[llvm] [Allocator] Keep bump pointer at a minimum alignment (PR #203718)

[Alexis Engelke via llvm-commits]

https://github.com/aengelke commented:

Direction looks good. Some questions. I won't have much time this week, but hopefully will be able to have a closer look in a few days.

https://github.com/llvm/llvm-project/pull/203718