MAPREDUCE-5976. native-task: should not fail to build if snappy is missing (Manu Zhang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/MR-2841@1616115 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5978. native-task: remove test case for not supported codec Bzip2Codec and DefaultCodec (Manu Zhang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/MR-2841@1616116 13f79535-47bb-0310-9956-ffa450edef68