[Analyzer] Checker for non-determinism caused by iteration of unordered container of pointers

Summary: Added a checker for non-determinism caused by iterating unordered containers like std::unordered_set containing pointer elements.

Reviewers: NoQ, george.karpenkov, whisperity, Szelethus, baloghadamsoftware

Reviewed By: Szelethus

Subscribers: mgorny, xazax.hun, baloghadamsoftware, szepet, rnkovacs, a.sidorin, mikhail.ramalho, donat.nagy, dkrupp, jdoerfert, Charusso, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59279

llvm-svn: 361664