base: add symbol support for dynamic libraries

Libraries are loaded into the process address space using the
mmap system call. Conveniently, this happens to be a good
time to update the process symbol table with the library's
incoming symbols so we handle the table update from within the
system call.

This works just like an application's normal symbols. The only
difference between a dynamic library and a main executable is
when the symbol table update occurs. The symbol table update for
an executable happens at program load time and is finished before
the process ever begins executing. Since dynamic linking happens
at runtime, the symbol loading happens after the library is
first loaded into the process address space. The library binary
is examined at this time for a symbol section and that section
is parsed for symbol types with specific bindings (global,
local, weak). Subsequently, these symbols are added to the table
and are available for use by gem5 for things like trace
generation.

Checkpointing should work just as it did previously. The address
space (and therefore the library) will be recorded and the symbol
table will be entirely recorded. (It's not possible to do anything
clever like checkpoint a program and then load the program back
with different libraries with LD_LIBRARY_PATH, because the
library becomes part of the address space after being loaded.)

base: remove fd from object loaders

All the object loaders directly examine the (already completely loaded
by object_file.cc) memory image. There is no current motivation to
keep the fd around.

Load the hypervisor symbols twice, once with an address mask so that we can get symbols for where it's copied to in memory
Add the ability to use an address mask for symbol loading
Rather then silently failing on platform accesses panic
Move BadAddr/IsaFake no Device from Tsunami
Let the system kernel be none, but warn about it

configs/common/FSConfig.py:
We don't have a kernel for sparc yet
src/arch/sparc/system.cc:
Load the hypervisor symbols twice, once with an address mask so that we can get symbols for where it's copied to in memory
src/base/loader/aout_object.cc:
src/base/loader/aout_object.hh:
src/base/loader/ecoff_object.cc:
src/base/loader/ecoff_object.hh:
src/base/loader/elf_object.cc:
src/base/loader/elf_object.hh:
src/base/loader/object_file.hh:
src/base/loader/raw_object.cc:
src/base/loader/raw_object.hh:
Add the ability to use an address mask for symbol loading
src/dev/sparc/t1000.cc:
Rather then silently failing on platform accesses panic
src/dev/sparc/t1000.hh:
fix up a couple of platform comments
src/python/m5/objects/Bus.py:
src/python/m5/objects/Device.py:
src/python/m5/objects/T1000.py:
src/python/m5/objects/Tsunami.py:
Move BadAddr/IsaFake no Device from Tsunami
src/python/m5/objects/System.py:
Let kernel be none
src/sim/system.cc:
Let the system kernel be none, but warn about it

Get SPARC to the point that it starts running. Add ability to load the ROM bin files, cleanup lockstep printing a bit
Since we don't have a platform yet, you need to comment out the default responder stuff in Bus.py to make it work.

SConstruct:
Add TARGET_ISA to the list of environment variables that end up in the build_env for python
configs/common/FSConfig.py:
add a simple SPARC system to being testing with, you'll need to change makeLinuxAlphaSystem to makeSparcSystem in fs.py for now
src/SConscript:
add a raw file object, at least until we get more info about how to compile openboot properly
src/arch/sparc/system.cc:
src/arch/sparc/system.hh:
add parameters for ROM files (OBP/Reset/Hypervisor), a ROM, load files into ROM
src/base/loader/object_file.cc:
src/base/loader/object_file.hh:
add option to try raw when nothing works
src/cpu/exetrace.cc:
cleanup lockstep printing a little bit
src/cpu/m5legion_interface.h:
change the instruction to be 32 bits because it is
src/mem/physical.cc:
fix assert that doesn't work if memory starts somewhere above 0
src/python/m5/objects/BaseCPU.py:
Add if statement to choose between sparc tlbs and alpha tlbs
src/python/m5/objects/System.py:
Add a sparc system that sets the rom addresses correctly
src/python/m5/params.py:
add the ability to add Addr() together