Symbol mangling for UDF prepare/close functions

Change-Id: If8f1386073f467e66ada74e606fc98f3344f0733
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1986
Reviewed-by: Skye Wanderman-Milne <skye@cloudera.com>
Tested-by: Skye Wanderman-Milne <skye@cloudera.com>