IMPALA-6825: Fix HADOOP_CLASSPATH when using Hadoop 3
IMPALA-6825: Fix HADOOP_CLASSPATH when using Hadoop 3

IMPALA-4277 added support for Hadoop 3. However, it omitted a component
from HADOOP_CLASSPATH that is required for the local minicluster to
access AWS.

I tested this manually and with this change the minicluster is able to
access HDFS.

Cherry-picks: not for 2.x

Change-Id: Ibe5784d32c6e8d04f147b26c7d2345609006ab46
Reviewed-on: http://gerrit.cloudera.org:8080/9956
Reviewed-by: Philip Zeyliger <3ba3974e96044dcde818e6310ed799abe10671d4@cloudera.com>
Tested-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>

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