Add --default-engine to pt-osc.

t/pt-online-schema-change/samples/default-engine.sql

@@ -0,0 +1,20 @@
+DROP DATABASE IF EXISTS pt_osc;
+CREATE DATABASE pt_osc;
+USE pt_osc;
+CREATE TABLE t (
+  id int auto_increment primary key,
+  c  char(32),
+  d  date,
+  unique index (c(32))
+) ENGINE=InnoDB;
+INSERT INTO pt_osc.t VALUES
+   (null, 'a', now()),
+   (null, 'b', now()),
+   (null, 'c', now()),
+   (null, 'd', now()),
+   (null, 'e', now()),
+   (null, 'f', now()),
+   (null, 'g', now()),
+   (null, 'h', now()),
+   (null, 'i', now()),
+   (null, 'j', now()); -- 10