Changes for Process object initialization in merged-memory environment.

Changes for Process object initialization in merged-memory environment.
System object now exists for both fullsys and syscall emulation, as the
latter needs it so that Process objects can find the shared PhysicalMemory
for initialization.
Changes are incomplete: still need to fix up Process (& EioProcess) memory
initialization and syscall emulation code for new mem interface.

arch/alpha/alpha_linux_process.cc:
arch/alpha/alpha_linux_process.hh:
arch/alpha/alpha_tru64_process.cc:
arch/alpha/alpha_tru64_process.hh:
cpu/base.cc:
cpu/base.hh:
    Take System argument in constructor.
cpu/exec_context.cc:
    Take System argument in constructor.
    Merge two constructors into a single one.
cpu/exec_context.hh:
    Take System argument in constructor.
    Merge two constructors into a single one.
    Replace dummy translation with lookup in Process object's page table.
python/m5/objects/Process.py:
    Add System parameter to Process object (& subobjects).
python/m5/objects/System.py:
    Segregate full-system only Process parameters (most of them!).
sim/process.cc:
    Take System argument in constructor.
    Move initialization to startup() callback to occur after system & cpus
    are initialized.
    Generate ProxyMemory object to pass to loader for transparent
    virtual page allocation.
sim/process.hh:
    Take System argument in constructor.
    Move initialization to startup() callback to occur after system & cpus
    are initialized.
sim/system.cc:
sim/system.hh:
    Enable System object for non-full-system too.
    Basically involved putting most of the existing code
    inside '#ifdef FULL_SYSTEM'.
    Key thing needed for syscall emulation at this point is
    the PhysicalMemory object (for Process initialization).

--HG--
extra : convert_revision : f0f34b47bd4f77b502191affd3d03b4d6d9bcdd8