Fix for Bug#12953 "Stored procedures: crash if OPTIMIZE TABLE in function"

OPTIMIZE TABLE statement is forbidden from usage in stored procedures/functions.

NOTE: OPTIMIZE TABLE statement can be useful in stored procedures. The idea is
that the user/administrator can create a stored procedure for admin
tasks (optimizing, backing up, etc). This procedure can be scheduled to run
automatically (by mean of internal cron (WL#1034)). So, once we can make this
statement work, it is worth doing it.

mysql-test/r/sp-error.result

@@ -758,3 +758,10 @@ execute stmt;
 ERROR 42000: FUNCTION test.bug11834_1 does not exist
 deallocate prepare stmt;
 drop function bug11834_2;
+DROP FUNCTION IF EXISTS bug12953|
+CREATE FUNCTION bug12953() RETURNS INT
+BEGIN
+OPTIMIZE TABLE t1;
+RETURN 1;
+END|
+ERROR 0A000: OPTIMIZE TABLE is not allowed in stored procedures