simulate.py: delay for a short time on success

Per discussion with Kent, a brief delay even if QEMU exits with a
successful status may be desirable, because there may have been a
failure in the simulated environment.

We have a shorter delay in part because we presume that the screen will
be more deciperhable in the QEMU-successful case, because QEMU will put
the terminal into a sensible state itself before terminating.
Experience will tell us how reliable this assumption is.

Tested success case with:
    ../griddle --SIMULATION=ON --PLATFORM=sabre
    ./simulate
Tested failure case with:
    ./simulate --extra-qemu-args bogus

cmake-tool/simulate_scripts/simulate.py

@@ -99,6 +99,9 @@ def notice(message):
         msg = "QEMU failed; resetting terminal in {d} seconds".format(d=delay) \
             + "--interrupt to abort\n"
         notice(msg)
-        time.sleep(delay)
+    else:
+        delay = 2  # in seconds
+
+    time.sleep(delay)
 
     subprocess.call("tput reset", shell=True)