GEODE-3203: fixing protobuf build.gradle to respect buildRoot
GEODE-3203: fixing protobuf build.gradle to respect buildRoot

Signed-off-by: Bruce Schuchardt <bschuchardt@pivotal.io>

This closes #632

davebarnes97/geode,jdeppe-pivotal/geode,jdeppe-pivotal/geode,charliemblack/geode,smgoller/geode,davebarnes97/geode,davinash/geode,PurelyApplied/geode,pdxrunner/geode,smanvi-pivotal/geode,masaki-yamakawa/geode,charliemblack/geode,masaki-yamakawa/geode,jdeppe-pivotal/geode,deepakddixit/incubator-geode,davinash/geode,pivotal-amurmann/geode,smanvi-pivotal/geode,davinash/geode,davebarnes97/geode,shankarh/geode,davinash/geode,pdxrunner/geode,davebarnes97/geode,deepakddixit/incubator-geode,masaki-yamakawa/geode,charliemblack/geode,pivotal-amurmann/geode,smanvi-pivotal/geode,davinash/geode,deepakddixit/incubator-geode,deepakddixit/incubator-geode,smgoller/geode,davebarnes97/geode,PurelyApplied/geode,PurelyApplied/geode,charliemblack/geode,pdxrunner/geode,shankarh/geode,davinash/geode,masaki-yamakawa/geode,pdxrunner/geode,smgoller/geode,jdeppe-pivotal/geode,PurelyApplied/geode,jdeppe-pivotal/geode,pivotal-amurmann/geode,smgoller/geode,PurelyApplied/geode,deepakddixit/incubator-geode,shankarh/geode,pdxrunner/geode,pdxrunner/geode,masaki-yamakawa/geode,davinash/geode,jdeppe-pivotal/geode,deepakddixit/incubator-geode,davebarnes97/geode,smgoller/geode,deepakddixit/incubator-geode,masaki-yamakawa/geode,pivotal-amurmann/geode,davebarnes97/geode,pdxrunner/geode,smanvi-pivotal/geode,smanvi-pivotal/geode,smgoller/geode,shankarh/geode,jdeppe-pivotal/geode,PurelyApplied/geode,pivotal-amurmann/geode,smgoller/geode,shankarh/geode,PurelyApplied/geode,masaki-yamakawa/geode,charliemblack/geode