Enable register windows.

Enable register windows.

arch/alpha/isa_traits.hh:
arch/mips/isa_traits.cc:
    Turned the integer register file into a class instead of a typedef to an array.
arch/alpha/regfile.hh:
    Changed the integer register file into a class instead of a typedef to an array. Also put the parts of the register file, ie the int, float, and misc register files, pc, npc, and nnpc, behind accessor functions. Added a changeContext function, and ContextParam and ContextVal types, so that things like the register window can be changed through call backs.
arch/mips/isa_traits.hh:
    Turned the integer register file into a class instead of a typedef to an array. Also moved a "using namespace" into the namespace definition.
arch/sparc/isa_traits.hh:
    Turned the integer register file into a class instead of a typedef to an array. Also "fixed" the max number of src and dest regs. They may need to be even larger.
arch/sparc/regfile.hh:
    Changed the integer register file into a class instead of a typedef to an array. Also put the parts of the register file, ie the int, float, and misc register files, pc, npc, and nnpc, behind accessor functions. Added a changeContext function, and ContextParam and ContextVal types, so that things like the register window can be changed through call backs. Created setCWP and setAltGlobals functions for the IntRegFile.
cpu/cpu_exec_context.hh:
    Used the accessor functions for the register file, and added a changeRegFileContext function to call back into the RegFile. Used the RegFile clear function rather than memsetting it to 0.
cpu/exec_context.hh:
    Added the changeRegFileContext function.
cpu/exetrace.cc:
    Use the TheISA::NumIntRegs constant, and use readReg now that the integer register file is a class instead of an array.
cpu/exetrace.hh:
    Get the address of the regs object, now that it isn't an array.

--HG--
extra : convert_revision : ea2dd81be1c2e66b3c684af319eb58f8a77fd49c