I now wonder if we can work around this at runtime by querying the deviceinfo.hardware setting. On nexus4 it should be the string 'mako'.  Ugly but if we don't do that we'll get lots and lots of bug reports about broken zoom on nexus4 from people who don't know they need a custom config.  The build-time config is really only intended for vendors creating master builds for their hardware and doesn't really help developers.