zlib: Use host if provided
zlib: Use host if provided

https://bugzilla.gnome.org/show_bug.cgi?id=768493

GStreamer/cerbero,EricssonResearch/cerbero,flexVDI/cerbero,OptoFidelity/cerbero,EricssonResearch/cerbero,OptoFidelity/cerbero,fluendo/cerbero,flexVDI/cerbero,justinjoy/cerbero,justinjoy/cerbero,EricssonResearch/cerbero,centricular/cerbero,fluendo/cerbero,atsushieno/cerbero,justinjoy/cerbero,flexVDI/cerbero,centricular/cerbero,GStreamer/cerbero,fluendo/cerbero,EricssonResearch/cerbero,OptoFidelity/cerbero,GStreamer/cerbero,EricssonResearch/cerbero,fluendo/cerbero,GStreamer/cerbero,flexVDI/cerbero,GStreamer/cerbero,nirbheek/cerbero,atsushieno/cerbero,flexVDI/cerbero,justinjoy/cerbero,atsushieno/cerbero,atsushieno/cerbero,fluendo/cerbero,atsushieno/cerbero,centricular/cerbero,nirbheek/cerbero,centricular/cerbero,centricular/cerbero,OptoFidelity/cerbero,nirbheek/cerbero,nirbheek/cerbero