Fix test: BigInteger.longValueExact added in 1.8
Fix test: BigInteger.longValueExact added in 1.8

Use longValue instead since it still verifies the fix
and works for Java 1.7.

armsargis/groovy,paulk-asert/groovy,bsideup/incubator-groovy,russel/groovy,dpolivaev/groovy,bsideup/incubator-groovy,apache/groovy,apache/groovy,apache/incubator-groovy,paulk-asert/incubator-groovy,jwagenleitner/groovy,paulk-asert/incubator-groovy,paulk-asert/groovy,dpolivaev/groovy,traneHead/groovy-core,dpolivaev/groovy,jwagenleitner/groovy,armsargis/groovy,traneHead/groovy-core,paulk-asert/incubator-groovy,jwagenleitner/incubator-groovy,paulk-asert/incubator-groovy,russel/groovy,jwagenleitner/incubator-groovy,shils/groovy,jwagenleitner/incubator-groovy,apache/groovy,russel/incubator-groovy,avafanasiev/groovy,shils/incubator-groovy,shils/groovy,jwagenleitner/groovy,russel/groovy,shils/groovy,avafanasiev/groovy,apache/incubator-groovy,shils/incubator-groovy,paulk-asert/incubator-groovy,russel/groovy,bsideup/incubator-groovy,jwagenleitner/groovy,bsideup/incubator-groovy,avafanasiev/groovy,dpolivaev/groovy,apache/incubator-groovy,apache/incubator-groovy,traneHead/groovy-core,russel/incubator-groovy,armsargis/groovy,paulk-asert/groovy,armsargis/groovy,shils/incubator-groovy,shils/incubator-groovy,apache/groovy,paulk-asert/groovy,russel/incubator-groovy,avafanasiev/groovy,traneHead/groovy-core,russel/incubator-groovy,jwagenleitner/incubator-groovy,shils/groovy