HandleAllocator: Fix heap ordering using std::greater. The default heap ordering is to return the greatest element in the heap. Since the handle allocator expects a minimal return value on a new allocation, this caused a bug. The bug is triggered by reserving handles, allocating new handles, then freeing the handles and allocating again with the same allocator. Fix the bug by using std::greater instead of std::less, which will make the heap return the smallest value instead of largest. Also adds some logging debugging code for the handle allocators. Bug: angleproject:1458 Change-Id: Ibef5dcbed0a664ccad0e0335f081e2355162584b Reviewed-on: https://chromium-review.googlesource.com/848644 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Frank Henigman <fjhenigman@chromium.org>