check for os and xcode version

[Joshua Root]

On 2017-10-6 10:00 , Helmut K. C. Tessarek wrote:
> I know I can check the OS release in portfiles with:
> 
> platform darwin X {
> 
> where X is the platform version.
> 
> It might be necessary to add fixes when OSX is Sierra/High Sierra AND
> Xcode 9.
> 
> How can I do this in the portfile?

Ideally fix the code such that it works with any Xcode version and avoid 
having to check, but if that's not possible, the xcodeversion variable 
is available in Portfiles. It's not a simple integer like os.major, so 
make sure you use the vercmp command when comparing versions (as opposed 
to '<', '>' or '==').

- Josh