Make the license header check an error for PRESUBMIT.

NOTRY=true

Review URL: https://codereview.chromium.org/100183003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238275 0039d316-1c4b-4281-b951-d872f2087c98

tools/android/checkstyle/chromium-style-5.0.xml

@@ -146,6 +146,7 @@
     <property name="message" value="Trailing whitespace"/>
     </module>
   <module name="RegexpHeader">
+    <property name="severity" value="error"/>
     <property name="header" value="^// Copyright 20\d\d The Chromium Authors. All rights reserved.$\n^// Use of this source code is governed by a BSD-style license that can be$\n^// found in the LICENSE file.$"/>
   </module>
 </module>