* config/rs6000/rs6000.h (RS6000_VARARGS_AREA, RS6000_VARARGS_SIZE):
	Remove.
	(STARTING_FRAME_OFFSET): Don't add RS6000_VARARGS_AREA.
	(machine_function): Move typedef to...
	* config/rs6000/rs6000.c (machine_function): ... here.  Add
	varargs_save_offset field.
	(rs6000_stack_t): Remove varargs_size field.
	(setup_incoming_varargs): Allocate varargs save area using
	assign_stack_local, try to make it as small as possible.
	Save offset from virtual_stack_vars_rtx to the save area
	in cfun->machine->varargs_save_offset.  Use UNITS_PER_FP_WORD
	instead of magic 8 when fp word byte size is used.
	(rs6000_va_start): Use cfun->machine->varargs_save_offset
	instead of -RS6000_VARARGS_SIZE.
	(rs6000_stack_info, debug_stack_info,
	rs6000_initial_elimination_offset): Remove all traces of
	varargs_size.
	* config/rs6000/sysv4.h (RS6000_VARARGS_AREA): Remove.
	* config/rs6000/darwin.h (STARTING_FRAME_OFFSET): Don't add
	RS6000_VARARGS_AREA.

From-SVN: r101655