Fixed Bug#21461026: INCONSISTEND CASING ON STORAGE ENGINE VARIABLE VALUES

Change the value of global variable internal_tmp_disk_storage_engine to use
consistent typo as other variables' value.

Author: Benny Wang

mysql-test/r/internal_tmp_disk_storage_engine.result

@@ -3116,6 +3116,14 @@ select distinct least(1,count(distinct a)) from t1 group by a;
 least(1,count(distinct a))
 0
 drop table t1;
+#
+# Bug#21461026: INCONSISTEND CASING ON STORAGE ENGINE VARIABLE VALUE
+#
+SHOW GLOBAL VARIABLES LIKE '%\_storage\_engine';
+Variable_name	Value
+default_storage_engine	InnoDB
+default_tmp_storage_engine	InnoDB
+internal_tmp_disk_storage_engine	InnoDB
 SET GLOBAL innodb_large_prefix=default;
 Warnings:
 Warning	131	Using innodb_large_prefix is deprecated and the parameter may be removed in future releases. See http://dev.mysql.com/doc/refman/5.7/en/innodb-file-format.html

mysql-test/t/internal_tmp_disk_storage_engine.test

@@ -1352,6 +1352,10 @@ insert into t1 values ('a');
 select distinct least(1,count(distinct a)) from t1 group by a;
 drop table t1;
 
+--echo #
+--echo # Bug#21461026: INCONSISTEND CASING ON STORAGE ENGINE VARIABLE VALUE
+--echo #
+SHOW GLOBAL VARIABLES LIKE '%\_storage\_engine';
 #============================end && cleanup======================= 
 SET GLOBAL innodb_large_prefix=default;
 set @@global.internal_tmp_disk_storage_engine= @old_internal_tmp_disk_storage_engine;

sql/sys_vars.cc

@@ -4015,7 +4015,7 @@ static Sys_var_plugin Sys_default_storage_engine(
        MYSQL_STORAGE_ENGINE_PLUGIN, DEFAULT(&default_storage_engine),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(check_storage_engine));
 
-const char *internal_tmp_disk_storage_engine_names[] = { "MYISAM", "INNODB", 0};
+const char *internal_tmp_disk_storage_engine_names[] = { "MyISAM", "InnoDB", 0};
 static Sys_var_enum Sys_internal_tmp_disk_storage_engine(
        "internal_tmp_disk_storage_engine",
        "The default storage engine for on-disk internal tmp table",