sim: have a curTick per eventq

This patch adds a _curTick variable to an eventq. This variable is updated
whenever an event is serviced in function serviceOne(), or all events upto
a particular time are processed in function serviceEvents(). This change
helps when there are eventqs that do not make use of curTick for scheduling
events.

src/base/vnc/vncinput.cc

@@ -46,6 +46,7 @@
 
 #include "base/vnc/vncinput.hh"
 #include "base/output.hh" //simout
+#include "base/trace.hh"
 #include "debug/VNC.hh"
 
 using namespace std;