[libc] [llvm] [llvm] Add KnownBits implementations for avgFloor and avgCeil (PR #86445)

[via llvm-commits]

goldsteinn wrote:

> > > looks like the BinaryExhaustive test fails when I remove the bool flag to enable Optimal check?
> > 
> > 
> > Oh, I thought this implementation was supposed to be optimal, but maybe I got that wrong.
> > Patch LGTM anyway.
> 
> I am assuming I need to put back the flag to disable optimality check ?

You already do. Its the `bool` argument.

https://github.com/llvm/llvm-project/pull/86445