[SPARK-6409][SQL] It is not necessary that avoid old inteface of hive, because...

[SPARK-6409][SQL] It is not necessary that avoid old inteface of hive, because this will make some UDAF can not work.

spark avoid old inteface of hive, then some udaf can not work like "org.apache.hadoop.hive.ql.udf.generic.GenericUDAFAverage"

Author: DoingDone9 <799203320@qq.com>

Closes #5131 from DoingDone9/udaf and squashes the following commits:

9de08d0 [DoingDone9] Update HiveUdfSuite.scala
49c62dc [DoingDone9] Update hiveUdfs.scala
98b134f [DoingDone9] Merge pull request #5 from apache/master
161cae3 [DoingDone9] Merge pull request #4 from apache/master
c87e8b6 [DoingDone9] Merge pull request #3 from apache/master
cb1852d [DoingDone9] Merge pull request #2 from apache/master
c3f046f [DoingDone9] Merge pull request #1 from apache/master