Re: Welcome to commercially driven open source...
Greed and nastiness??
Surely the same is true of non-commercial open source projects too: they will only support Solaris if there is interest from their user base and their developers.
Autotools takes you some of the way - if used properly, POSIX code will build. But I wouldn't expect every project to set up CI for solaris, or to build binary releases for Solaris.
Indeed, for *non-commercial* projects there is less incentive to do so. The *commercial* projects are the ones with customers who say "I must run this on AIX" or "I must run this on Solaris". The non-commercial ones are relying on the time of volunteers only.