Got hello world to work!

Got hello world to work!

arch/sparc/isa/decoder.isa:
    Made sure if a register was assigned to along some control path, then all paths on which no exception would block commit set a value as well. Also, Rs1 is treated as signed for bpr instructions.
arch/sparc/isa/formats/integerop.isa:
    Added an IntOpImm11 class which sign extends the SIMM11 immediate field.
arch/sparc/isa/formats/mem.isa:
    Fixed how offsets are used, and how disassembly is generated.
arch/sparc/linux/process.cc:
    Added fstat and exit_group syscalls.

--HG--
extra : convert_revision : 3b4427d239d254a92179a4137441125b8a364264