Support loading in a symbol file.

Support loading in a symbol file.

arch/alpha/freebsd/system.cc:
arch/alpha/isa/decoder.isa:
arch/alpha/linux/system.cc:
arch/alpha/system.cc:
arch/alpha/tru64/system.cc:
    Let symbol files be read in so that profiling can happen on the binaries as well.
python/m5/objects/System.py:
    Add in symbol files.
sim/pseudo_inst.cc:
    Load in a specified symbol file.
sim/pseudo_inst.hh:
    Allow for symbols to be loaded.
sim/system.hh:
    Support symbol file.
util/m5/m5.c:
util/m5/m5op.S:
    Add support to m5 util for loading symbols (and readfile).

--HG--
extra : convert_revision : f10c1049bcd7b22b98c73052c0666b964aff222b