Changes to start making the tree use the new memory system. Trying to compile decode...

Changes to start making the tree use the new memory system.  Trying to compile decoder.cc but fails still.

SConscript:
    Place the memory objects back in the right place
arch/alpha/isa_desc:
    Fix includes to point to the new memory requests
cpu/exec_context.hh:
    Exec context now points to memory object, fix the include paths.
    Convert to prot_read/prot_write functions instead of read and write.
    Convert to new CpuRequestPtr instead of MemReqPtr.
mem/request.hh:
    Add back in support for Request Flags (needed by decoder to tag request) Removed the flags that were associated with packets/coherence.
sim/process.hh:
    Converted to point to new memory objects

--HG--
extra : convert_revision : a0b95380915d63b53194e2a26336d6adb1a0086b