[Attributor] Use the white list for attributes consistently

Summary:
We create attributes on-demand so we need to check the white list
on-demand. This also unifies the location at which we create,
initialize, and eventually invalidate new abstract attributes.

The tests show mixed results, a few more call site attributes are
determined which can cause more iterations.

Reviewers: uenoku, sstefan1

Subscribers: hiraditya, bollu, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66913

llvm-svn: 370922