should we use new c macros included with rubyc?

[dsisnero]

with ruby/ruby#3983 , rubyc includes c macros to do atomic operations. should we use these for the atomic operations?

• Operating system: linux / mac / win
• Ruby implementation: Ruby / JRuby / TruffleRuby / Rubinius
• concurrent-ruby version: x.y.z
• concurrent-ruby-ext installed: yes / no
• concurrent-ruby-edge used: yes / no

[pitr-ch]

This is a good idea, thank you for letting me know. Although, the implementation in concurrent-ruby should use these conditionally only when available since it has to support old Ruby versions.