IMPALA-911: Periodically release memory in tcmalloc.

Change-Id: Ifc3d544b7bdc4caa2f238ae13cab6a62cfc587f9
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2066
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins
Fix the tpcds count queries test.

Because of a malformed .test file, TPCDS-COUNT-PROMOTION was never run because of a
missing section delimiter. This patch fixes the .test file and adds the delimiter.

Change-Id: Ifd0fa5db1c2bb84815fc66e981e6a989e6c217e4
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2017
Reviewed-by: Ishaan Joshi <ishaan@cloudera.com>
Tested-by: jenkins