Get rid of SocketServer::checkTimeouts()

It doesn't belong on each socket server object as timers are global.
Force implementations to call the Timer system directly instead,
avoiding any middle men.
diff --git a/unix/x0vncserver/x0vncserver.cxx b/unix/x0vncserver/x0vncserver.cxx
index 4c8f0bf..5f6c9f4 100644
--- a/unix/x0vncserver/x0vncserver.cxx
+++ b/unix/x0vncserver/x0vncserver.cxx
@@ -322,7 +322,7 @@
         }
       }
 
-      soonestTimeout(&wait_ms, server.checkTimeouts());
+      soonestTimeout(&wait_ms, Timer::checkTimeouts());
 
       tv.tv_sec = wait_ms / 1000;
       tv.tv_usec = (wait_ms % 1000) * 1000;
@@ -357,7 +357,7 @@
         }
       }
 
-      server.checkTimeouts();
+      Timer::checkTimeouts();
 
       // Client list could have been changed.
       server.getSockets(&sockets);