should we use new c macros included with rubyc?

with https://github.com/ruby/ruby/pull/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

Start by reading Ruby PR 3983 and locating the existing atomic-operation implementation in concurrent-ruby-ext. Compare the new rubyc C macros across Linux, macOS, and Windows and consider the listed Ruby implementations; done means a resolved compatibility decision with appropriate coverage if the macros are adopted.