While operand bundles carry unpredictable semantics, we know some of
them and can therefore "ignore" them. In this case we allow to look at
the declaration of `llvm.assume` when asked for the attributes at a call
site. The assume operand bundles we have do not invalidate the
declaration attributes.
We cannot test this in isolation because the llvm.assume attributes are
determined by the parser. However, a follow up patch will provide test
coverage.