Fix surfaceflinger on integer sanitized builds.

Refactors unsigned integer overflows in do_compare to fix integer
overflow sanitized builds. Also disables sanitization in
Layer::makeTraversalList.

Test: Compiled and checked output from sanitizer.
Bug: 30969751
Change-Id: I1a6d73435495e8b3ba3edb2587f62e4a0f2662f3