stop m5 from leaking like a sieve

stop m5 from leaking like a sieve
don't create a new physPort/virtPort every time activateContext() is called
add the ability to tell a memory object to delete it's reference to a port and a method to have a port call deletePortRefs()
on the port owner as well as delete it's peer
still need to stop calling connectMemoPorts() every time activateContext() is called or we'll overflow the bus id and panic

src/cpu/thread_state.cc:
    if we hav ea (phys|virt)Port don't create a new on, have it delete it's peer and then reuse it
src/mem/bus.cc:
src/mem/bus.hh:
    add ability to delete a port by usig a hash_map instead of an array to store port ids
    add a function to do deleting
src/mem/cache/cache.hh:
src/mem/cache/cache_impl.hh:
src/mem/mem_object.cc:
src/mem/mem_object.hh:
    adda function to delete port references from a memory object
src/mem/port.cc:
src/mem/port.hh:
    add a removeConn function that tell the owener to delete any references to the port and then deletes its peer

--HG--
extra : convert_revision : 272f0c8f80e1cf1ab1750d8be5a6c9aa110b06a4