Numerous bug fixes:

-- passing FP arguments to functions with more than 6 arguments
-- passing FP arguments to varargs functions
-- passing FP arguments to functions with no prototypes
-- incorrect coloring for CC registers (both int and FP): interferences
   were being completely ignored for int CC and were considered but no
   spills were marked for fp CC!

Also some code improvements:
-- better interface to generating machine instr for common cases
   (many places still need to be updated to use this interface)
-- annotations on MachineInstr to communicate information from
   one codegen phase to another (now used to pass information about
   CALL/JMPLCALL operands from selection to register allocation)
-- all sizes and offests in class TargetData are uint64_t instead of uint

llvm-svn: 2642