HHVM-203: Client construction should use mongoc_write_concern_is_valid()
HHVM-203: Client construction should use mongoc_write_concern_is_valid()

mongodb-labs/mongo-hhvm-driver-prototype,mongodb-labs/mongo-hhvm-driver-prototype,mongodb/mongo-hhvm-driver,10gen-labs/mongo-hhvm-driver-prototype,mongodb/mongo-hhvm-driver,10gen-labs/mongo-hhvm-driver-prototype,jmikola/mongo-hhvm-driver-prototype,mongodb-labs/mongo-hhvm-driver,jmikola/mongo-hhvm-driver-prototype,mongodb-labs/mongo-hhvm-driver,mongodb-labs/mongo-hhvm-driver,jmikola/mongo-hhvm-driver,jmikola/mongo-hhvm-driver-prototype,mongodb/mongo-hhvm-driver,mongodb-labs/mongo-hhvm-driver-prototype,jmikola/mongo-hhvm-driver,10gen-labs/mongo-hhvm-driver-prototype,10gen-labs/mongo-hhvm-driver-prototype,jmikola/mongo-hhvm-driver-prototype,jmikola/mongo-hhvm-driver,mongodb-labs/mongo-hhvm-driver-prototype,jmikola/mongo-hhvm-driver,mongodb/mongo-hhvm-driver,mongodb-labs/mongo-hhvm-driver