Implement more m5 pseduo opcodes:

Implement more m5 pseduo opcodes:
resetstats
dumpstats
dumpresetstats
m5checkpoint

Lots of cleanup of serialization and stats dumping/resetting to
work with these new instructions

arch/alpha/isa_desc:
    Implement more m5 pseduo opcodes:
    resetstats
    dumpstats
    dumpresetstats
    m5checkpoint

    All of these functions take two optional parameters, the first is a delay,
    and the second is a period.  The delay tells the simulator to wait the
    specified number of nanoseconds before triggering the event, the period
    tells the simulator to repeat the event with a specified frequency
base/statistics.cc:
base/statistics.hh:
    regReset RegResetCallback
dev/disk_image.cc:
    serializeFilename -> CheckpointFile()
sim/debug.cc:
    Move this debugging statement to sim_stats.cc
sim/eventq.cc:
    Don't AutoDelete an event if it is scheduled since the process()
    function could potentially schedule the event again.
sim/main.cc:
    DumpStatsEvent is now Statistics::SetupEvent(Dump, curTick)
sim/serialize.cc:
    Change the serialize event so that it's possible to cause the
    event to repeat.  Also make the priority such that the event
    happens just before the simulator would exit if both events
    were scheduled for the same cycle.

    get rid of the serializeFilename variable and provide a CheckpointFile()
    function.  This function takes a basename that is set in the
    configuration, and appends the current cycle to the name so that
    multiple checkpoints can be dumped from the same simulation.

    Also, don't exit the simulation when a checkpoint file is dumped.
sim/serialize.hh:
    serializeFilename -> CheckpointFile()
    SetupCheckpoint function to tell the simulator to prepare
    to checkpoint at a certain time with a certain period
sim/sim_events.cc:
    DumpStatsEvent stuff gets move to sim_stats.(cc|hh)
    The context stuff gets moved into the already existing
    stats context in stat_context.cc
sim/sim_events.hh:
    DumpStatsEvent stuff gets move to sim_stats.(cc|hh)
sim/universe.cc:
    Provide some simple functions for converting times into
    ticks.  These use floating point math to get as close as
    possible to the real values.  Multipliers are set up ahead
    of time

--HG--
extra : convert_revision : d06ef26a9237529a1e5060cb1ac2dcc04d4ec252