This is what I had to change to compile varnish-nagios again (on FreeBSD). The simple change is to fix what commit varnish/Varnish-Cache@96f5919e56f4a5895c53e9bfc98cf643c4ea0ca6 broke
Thanks for the PR, however your patch would have broken compatibility with varnish 4.0.x. I did however commit a fix that builds on varnish 3.x, 4.0.x and 4.1.
This is what I had to change to compile varnish-nagios again (on FreeBSD). The simple change is to fix what commit varnish/Varnish-Cache@96f5919e56f4a5895c53e9bfc98cf643c4ea0ca6 broke