OF-653: Avoid deadlock between session reaper and BOSH terminate request

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/trunk@13557 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/openfire/http/HttpSession.java

@@ -1000,10 +1000,8 @@ public class HttpSession extends LocalClientSession {
     }
 
     private void closeSession() {
-    	synchronized (this) {
-	        if (isClosed) { return; }
-	        isClosed = true;
-    	}
+        if (isClosed) { return; }
+        isClosed = true;
 
         // close connection(s) and deliver pending elements (if any)
         synchronized (connectionQueue) {