Add test for str_to_time

mysql-test/r/func_time.result

@@ -184,3 +184,5 @@ extract(MINUTE_SECOND FROM "10:11:12")
 1112
 extract(SECOND FROM "1999-01-02 10:11:12")
 12
+ctime	hour(ctime)
+2001-01-12 12:23:40	12

mysql-test/t/func_time.test

@@ -98,3 +98,10 @@ select extract(HOUR_SECOND FROM "10:11:12");
 select extract(MINUTE FROM "10:11:12");
 select extract(MINUTE_SECOND FROM "10:11:12");
 select extract(SECOND FROM "1999-01-02 10:11:12");
+
+drop table if exists t1;
+create table t1 (ctime varchar(20));
+insert into t1 values ('2001-01-12 12:23:40');
+select ctime, hour(ctime) from t1;
+drop table t1;
+