Improve DELETE with JOIN handling to avoid subqueries if possible

Before:

```
  Pet Destroy (0.8ms)  DELETE FROM `pets` WHERE `pets`.`pet_id` IN (SELECT `pet_id` FROM (SELECT DISTINCT `pets`.`pet_id` FROM `pets` LEFT OUTER JOIN `toys` ON `toys`.`pet_id` = `pets`.`pet_id` WHERE `toys`.`name` = ?) AS __active_record_temp)  [["name", "Bone"]]
```

After:

```
  Pet Destroy (1.0ms)  DELETE `pets` FROM `pets` LEFT OUTER JOIN `toys` ON `toys`.`pet_id` = `pets`.`pet_id` WHERE `toys`.`name` = ?  [["name", "Bone"]]
```

activerecord/lib/arel/visitors/mysql.rb

@@ -75,14 +75,7 @@ def prepare_update_statement(o)
             o
           end
         end
-
-        def prepare_delete_statement(o)
-          if o.offset || has_join_sources?(o)
-            super
-          else
-            o
-          end
-        end
+        alias :prepare_delete_statement :prepare_update_statement
 
         # MySQL is too stupid to create a temporary table for use subquery, so we have
         # to give it some prompting in the form of a subsubquery.

activerecord/lib/arel/visitors/to_sql.rb

@@ -76,7 +76,13 @@ def compile(node, collector = Arel::Collectors::SQLString.new)
         def visit_Arel_Nodes_DeleteStatement(o, collector)
           o = prepare_delete_statement(o)
 
-          collector << "DELETE FROM "
+          if has_join_sources?(o)
+            collector << "DELETE "
+            visit o.relation.left, collector
+            collector << " FROM "
+          else
+            collector << "DELETE FROM "
+          end
           collector = visit o.relation, collector
 
           collect_where_for(o, collector)