MariaDB 10.2.2: optimization tests are failed on some platforms

[kou]

All platforms: http://buildbot.askmonty.org/buildbot/grid?category=main&branch=ks-10.2-Mroonga-6.08

Failed platforms:

• http://buildbot.askmonty.org/buildbot/builders/bld-dan-debug/builds/3637
• http://buildbot.askmonty.org/buildbot/builders/bld-dan-release/builds/3908

Log: http://buildbot.askmonty.org/buildbot/builders/bld-dan-debug/builds/3637/steps/test_1/logs/stdio

----
CURRENT_TEST: mroonga/storage.optimization_count_skip_index_equal
--- /opt/buildbot-slave/mariadb/dan_demeter2/build/storage/mroonga/mysql-test/mroonga/storage/r/optimization_count_skip_index_equal.result  2016-09-03 14:06:58.511315734 -0400
+++ /opt/buildbot-slave/mariadb/dan_demeter2/build/storage/mroonga/mysql-test/mroonga/storage/r/optimization_count_skip_index_equal.reject  2016-09-03 21:00:37.660285054 -0400
@@ -14,5 +14,5 @@
 3
 SHOW STATUS LIKE 'mroonga_count_skip';
 Variable_name  Value
-Mroonga_count_skip 1
+Mroonga_count_skip 0
 DROP TABLE users;

mysqltest: Result content mismatch
----

----
CURRENT_TEST: mroonga/storage.optimization_count_skip_index_equal
--- /opt/buildbot-slave/mariadb/dan_demeter2/build/storage/mroonga/mysql-test/mroonga/storage/r/optimization_count_skip_index_equal.result  2016-09-03 14:06:58.511315734 -0400
+++ /opt/buildbot-slave/mariadb/dan_demeter2/build/storage/mroonga/mysql-test/mroonga/storage/r/optimization_count_skip_index_equal.reject  2016-09-03 21:00:38.714285054 -0400
@@ -14,5 +14,5 @@
 3
 SHOW STATUS LIKE 'mroonga_count_skip';
 Variable_name  Value
-Mroonga_count_skip 1
+Mroonga_count_skip 0
 DROP TABLE users;

mysqltest: Result content mismatch
----

Failing test(s):
   mroonga/storage.optimization_count_skip_index_equal
   mroonga/storage.optimization_count_skip_primary_key_equal

[kou]

test/run-sql-test.sh --ps-protocol reproduces it.

[kou]

The fix breaks the test without --ps-protocol case.
We shouldn't use select_lex->where->next. select_lex->where itself contains all conditions.