Checkstyle fix - Added file header.

hibernate-core/src/main/java/org/hibernate/dialect/PostgreSQL93Dialect.java

@@ -1,3 +1,9 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
 package org.hibernate.dialect;
 
 import java.util.List;