Move activity tracking code into its own class. Now the CPU no longer has to keep...

Move activity tracking code into its own class.  Now the CPU no longer has to keep track of the activity tracking internals; it just calls advance() on the class and uses it to tell if it should deschedule itself.

SConscript:
    Split off activity/idling code into its own class to do the processing separately.
cpu/o3/alpha_cpu_builder.cc:
cpu/o3/alpha_params.hh:
    Activity stuff.  This is mostly for debugging and may be removed later on (or changed to enable/disable activity idling).
cpu/o3/cpu.cc:
    Move activity idling stuff mostly into its own class, so it no longer clutters this file.
cpu/o3/cpu.hh:
    Move activity idling stuff into its own class.
python/m5/objects/AlphaFullCPU.py:
    Add parameter for initial activity value.

--HG--
extra : convert_revision : f32f7cc03895dc07ab57ddba78c5402a1a8b0f1a