* rs6000-tdep.c (rs6000_software_single_step): Use

	* rs6000-tdep.c (rs6000_software_single_step): Use
	rs6000_breakpoint_from_pc() to fetch breakpoint instruction
	and size.  Use target_insert_breakpoint() and
	target_remove_breakpoint() to insert and remove breakpoints
	instead of explicit memory reads and writes.