s6: compatibility with make<3.82

From: Buck Evan <buck_at_yelp.com>
Date: Tue, 21 Jul 2015 09:36:41 -0700

Apparently the 'private' keyword was added in 3.82, but many of the
platforms I care about have older versions of make.

Would you accept a patch to factor it out?
Received on Tue Jul 21 2015 - 16:36:41 UTC