[SPARK-19409][BUILD] Fix ParquetAvroCompatibilitySuite failure due to test dependency on avro.

Author: dongjoon-hyun

sql/core/pom.xml

@@ -129,6 +129,12 @@
       <artifactId>parquet-avro</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.apache.avro</groupId>
+      <artifactId>avro</artifactId>
+      <version>1.8.0</version>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>