Optimize local and bulk management of hazptr_holder-s

Optimize local and bulk management of hazptr_holder-s

Summary:
Changes:
- Added hazptr_local<M> for optimized management of local hazptr_holder-s.
- Added hazptr_array<M> for optimized management of hazptr_holder-s
- Added benchmarks for hazptr_local and hazptr_array
- Added tests for hazptr_local and hazptr_array
- Changed SWMRList example to use hazptr_local<2> instead of two hazptr_holder-s.
- Updated benchmark performance results.

Reviewed By: davidtgoldblatt

Differential Revision: D5833721

fbshipit-source-id: 154811f67c38abac7342cecb71f829778ccf76b2