NOJIRA: Xcode 9.1 update. Fix build break use NULL vs 0 for comparison
NOJIRA: Xcode 9.1 update. Fix build break use NULL vs 0 for comparison

openweave/openweave-core,openweave/openweave-core,openweave/openweave-core,openweave/openweave-core,openweave/openweave-core,openweave/openweave-core