IMPALA-846: Add additional regression test.

This issue has coincidentally been resolved by the fix for IMPALA-820.
This patch adds an additional regression test for explicitly covering
IMPALA-846.

Change-Id: Ib60174676e5bb53de543a1db30adc05cef4d6593
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1719
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins
Admission controller: Separate TPoolStats mem_usage and mem_estimate

Change-Id: I521de3a99faca3aaf10e3900a4a12b0d2fa7a0f3
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1704
Reviewed-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: jenkins
[CDH4] Add third-party jar containing Yarn classes used by Impala

This is necessary because Impala has an admission controller that is configured
using the same configuration as Llama and Yarn (i.e. a fair-scheduler.xml and
llama-site.xml). Some Yarn classes (available in CDH5 only) are used to provide
user to pool resolution, authorization, and accessing pool configurations.
Impala needs these classes on the classpath in order to support CDH4, so they're
built as a separate third-party jar. For CDH5, this jar is not necessary and
will not be included as a dependency. Because this exists in CDH4 only, this
lives in third-party along with other CDH version-specific dependencies.

Change-Id: I85fc19a86f26df659400434a9c4f186d0029545c
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1565
Reviewed-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: jenkins
Consistent memory estimates for explain tests.

Our new build machines (e.g., beefy) have more cores than our other machines,
so scan nodes may have a different memory estimate causing the explain tests
to fail. This patch fixes the num_scanner_threads to 1 for explain tests
to ensure consisteny estimates.

Change-Id: Ie6194f3c3b17d04aa141d04fcddb7ac948e92fcf
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1735
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins