Version identifier for PS4

[Johan Engelen via Digitalmars-d]

Hi all,
  PR 5850 is proposing to add a predefined (reserved) version 
identifier for the PS4 OS: "PS4" [1].
Thanks for your comment (preferably with an alternative 
suggestion in case you don't like "PS4").

Thanks,
  Johan

[1] https://github.com/dlang/dmd/pull/5850