Fix so that O3CPU doesnt segfault on exit.

Fix so that O3CPU doesnt segfault on exit.
Major thing was to not execute commit if there are no active threads in CPU.

src/cpu/o3/alpha/thread_context.hh:
    call deallocate instead of deallocateContext
src/cpu/o3/commit_impl.hh:
    dont run commit stage if there are no instructions
src/cpu/o3/cpu.cc:
    add deallocate event, deactivateThread function, and edit deallocateContext.
src/cpu/o3/cpu.hh:
    add deallocate event and add optional delay to deallocateContext
src/cpu/o3/thread_context.hh:
    optional delay for deallocate
src/cpu/o3/thread_context_impl.hh:
    edit DPRINTFs to say Thread Context instead of Alpha TC
src/cpu/thread_context.hh:
    optional delay
src/sim/syscall_emul.hh:
    name stuff

--HG--
extra : convert_revision : f4033e1f66b3043d30ad98dcc70d8b193dea70b6