Updates for serialization. As long as the tickEvent doesn't need to be serialized...

Updates for serialization.  As long as the tickEvent doesn't need to be serialized (I don't believe it does because we drain all CPUs prior to checkpointing), it should be feasible to start up from other CPU's checkpoints.

src/cpu/simple/atomic.cc:
src/cpu/simple/atomic.hh:
src/cpu/simple/base.cc:
src/cpu/simple/timing.cc:
src/cpu/simple_thread.cc:
    Updates for serialization.

--HG--
extra : convert_revision : 0f150de75d4bc833e4c9b83568e7fd22688d5727