Xcode configuration woes

[Vincent Habchi]

Ryan,

> It failed to build on the 10.11 and older buildbot workers not because of qgis3 but because of its dependency postgresql10:
> 
> https://trac.macports.org/ticket/57588

Good news it built on 10.12+ though.

Turns out I’m at PostgreSQL conference today, so I’ll try to ask about that to one of the attending developers. 

Thanks for giving a look!
Vincent