IMPALA-1110: group_concat agg function does not work with optional separator.

Rather than omit the first separator in each intermediate result,
always include the separator, but also remember the length of the
first separator.  Then, during finalize, remove whichever separator
string ends up at the beginning of the final merged result.

Change-Id: I6de7d1cda1a43b8de7d03c6798ec9667ffa457f8
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3669
Reviewed-by: Marcel Kornacker <marcel@cloudera.com>
Tested-by: jenkins
Thrift structs for AnalyticNode

Adds thrift structures for the evaluation of analytic functions.

Change-Id: I6c60d658fce0b1ec7ccf52b1bde79af599562b17
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3646
Reviewed-by: Marcel Kornacker <marcel@cloudera.com>
Tested-by: jenkins
Skipping to run TestUnsupportedInsertFormats test for compressed test.

Realized that if we run it with text/codec it will successfully insert a record
("hi", "there") in tinytable, which is undesirable. Skipping this test for
compressed text.

Change-Id: I8076f4fcac17d7f7530ac4993b0d4b3bd89d5fa0
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3668
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins