Version Identifiers for Platforms / Architectures not supported by DMD

[Iain Buclaw]

I have had a recent pull request regarding the updating of some of GDC's OS
and Arch version identifiers.

https://bitbucket.org/goshawk/gdc/pull-request/2/make-some-system-and-cpu-version

Such changes include, aix -> AIX; ALPHA -> Alpha;  and a few more.


While I welcome any change suggestions, I would love to hear the opinion of D
users on the proposed change.


Regards
Iain