Don't warn if no Contact is received in a 387 SIP answer, that's used for something else.

git-svn-id: http://voip.null.ro/svn/yate@5509 acf43c95-373e-0410-b603-e72c3f656dc1

modules/ysipchan.cpp

@@ -5918,7 +5918,7 @@ bool YateSIPConnection::process(SIPEvent* ev)
 			parameters().addParam("divert_screen",tmp);
 		}
 	    }
-	    else
+	    else if (code != 387)
 		Debug(this,DebugMild,"Received %d redirect without Contact [%p]",code,this);
 	}
 	paramMutex().unlock();