Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54926
Re-order the validation checks.
Order is now:
- Is this a WebSocket upgrade?
- Is there a matching endpoint?
- Validate remaining headers

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1479061 13f79535-47bb-0310-9956-ffa450edef68