Significant changes to correctly spill CC registers and to correctly

handle conditional move instructions:
-- cpMem<->Reg functions now support CC registers (int and FP) correctly.
   Also, cpMem<->Reg functions now return a vector of machine instructions.
-- Scratch registers must be explicitly provided to cpMem<->Reg when
   needed, since CC regs need one to be copied to/from memory.
-- CC regs are saved to a scratch register instead of stack.
-- All regs used by a instruction are now recorded in MachineInstr::regsUsed,
   since regs used to save values *across* an instruction are not obvious
   either from the operands or from the LiveVar sets.
-- An (explicit or implicit) operand may now be both a def and a use.
   This is needed for conditional move operations.
   So an operand may need spill code both before and after the instruction.

Other changes:
-- Added several get{Class,Type} functions.
-- Added unified-to-local register number conversion.
-- class MachineCodeForBasicBlock is now an annotation on BasicBlock.
-- Suggest/Color methods may modify the MachineInstr (and always did),
   so don't make that argument const!
-- Caller-saving code doesn't need its special purpose code for
   handling CC registers since cpMem<->Reg handle those correctly now.

llvm-svn: 2834