Support Solaris

[tropikhajma]

Many of the demos build and run on Solaris out of the box, some only need a minor tweak.
It'd be nice to at least not block building them on Solaris.

The two commits in my fork of the project make about half of the demos build and run on Solaris 11.4 on x86:
tropikhajma@d04fb7f
tropikhajma@ae804c9

[mmdriley]

@tropikhajma -- thank you for this work! We're very interested in Safeside covering a breadth of platforms and Solaris would be a welcome addition.

What would be the best way for us to set up a Solaris build in CI? Travis lets us use nested virtualization, if that's helpful for putting together a solution.

I apologize, it will be a bit before I have a chance to look at these changes; I have some competing work with deadlines in mid-July. But I look forward to digging in later this month.