Added dummy checkstyle and test targets to liferay module

The main build is currently assuming that every submodule has
a checkstyle and a test target. Added a dummy implementation for both of
them so the build passes.

Change-Id: Iea29b25840c26a4a384ba1ce8293d9ea6f37981e

liferay/build.xml

@@ -69,4 +69,8 @@
         <antcall target="common.clean" />
     </target>
 
-</project>
+    <target name="checkstyle" />
+
+    <target name="test" depends="checkstyle" />
+
+</project>