Add support for serialization

base/pollevent.hh:
    Add queued() member function to indicate if this event has been queued

--HG--
extra : convert_revision : bebb04dc8e10c1043e55e0036806bd1ca4fec167

base/pollevent.hh

@@ -50,6 +50,8 @@ class PollEvent
     void disable();
     void enable();
     virtual void process(int revent) = 0;
+
+    bool queued() { return queue != 0; }
 };
 
 class PollQueue