[LICM/AST] Check if the AliasAny set is removed from the tracker.

Summary:
Resolves PR38513.
Credit to @bjope for debugging this.

Reviewers: hfinkel, uabelho, bjope

Subscribers: sanjoy.google, bjope, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67417

llvm-svn: 371752