[llvm] [IR] Do not inherit ABI attributes from the callee (PR #207173)

[Ulrich Weigand via llvm-commits]

uweigand wrote:

> I think s390x buildbot failure is because of this: https://clang.godbolt.org/z/7dK9YoMKW We're generating ldexp without signext here.
> 
> Edit: Oh, I see that it's generated on the function declaration, but not on the call. That's concerning.

`llvm::getOrInsertLibFunc` in `lib/Transforms/Utils/BuildLibCalls.cpp` sets the target-required signext/zeroext attributes on the function declaration for any library routines emitted by middle-end optimization.  But I don't see anything setting attributes on the call arguments there ... maybe this actually relied on the inheritance that used to happen?

https://github.com/llvm/llvm-project/pull/207173