Log Message:
p5-Alien-Build: another SunOS + pkgconf build support fix

Don't assume pkgconf won't work on Solaris derivates and disallow its
use. (This package being a tool that's used by other packages for
builds.) Addresses a failure of p5-Alien-LibGumbo to build on SunOS
only. There was more than one functional path that may or may not be
called by dependent packages here for pkgconf support.