Stabilize two new tests in MySQL-5.6.17

Summary:
Feature: Basic Test Fixes

These two new tests in 5.6.17 added some selects without ORDER BY:
1) main.partition_index_innodb
2) main.partition_index_myisam

So, the result files may not match, even if their results are correct.

This fixes that.

Test Plan:
Before these change were made, these tests showed failures after
later (correct) changes were added, while rebasing the Facebook
branch onto WebScaleSQL-5.6.17.

mtr main.partition_index_innodb main.partition_index_myisam

Verified the only output changes were "ORDER BY" and result order.

Reviewers: pivanof, inaam-rana, darnaut

Reviewed By: pivanof

CC: WebScaleSQL

Differential Revision: https://reviews.facebook.net/D17637