* va-ppc.h (__va_start_common): Let __builtin_saveregs do the work.
* rs6000.c (expand_builtin_saveregs): For V4, initialize a private
va_list struct, and return a pointer to it.
(setup_incoming_varargs): V4 save area based off virtual_stack_vars
instead of frame_pointer.
From-SVN: r26710
