[SPARK-3039] [BUILD] Spark assembly for new hadoop API (hadoop 2) contains avro-mapred for

hadoop 1 API had been marked as resolved but did not work for at least some
builds due to version conflicts using avro-mapred-1.7.5.jar and
avro-mapred-1.7.6-hadoop2.jar (the correct version) when building for hadoop2.

sql/hive/pom.xml org.spark-project.hive:hive-exec's depends on 1.7.5:

Building Spark Project Hive 1.2.0
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.4:tree (default-cli) @ spark-hive_2.10 ---
[INFO] org.apache.spark:spark-hive_2.10:jar:1.2.0
[INFO] +- org.spark-project.hive:hive-exec:jar:0.13.1a:compile
[INFO] |  \- org.apache.avro:avro-mapred:jar:1.7.5:compile
[INFO] \- org.apache.avro:avro-mapred:jar:hadoop2:1.7.6:compile
[INFO]

Excluding this dependency allows the explicitly listed avro-mapred dependency
to be picked up.

Author: medale

pom.xml

@@ -938,6 +938,10 @@
             <groupId>com.esotericsoftware.kryo</groupId>
             <artifactId>kryo</artifactId>
           </exclusion>
+          <exclusion>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro-mapred</artifactId>
+          </exclusion>
         </exclusions>
       </dependency>
       <dependency>