* cfglayout.c (cfg_layout_duplicate_bb): Do not update frequencies
	at all if edge is not specified.
	(can_copy_bbs_p, copy_bbs): New.
	* cfglayout.h (can_copy_bbs_p, copy_bbs): Declare.
	* cfgloop.c (get_loop_body): Comment more precisely.
	* cfgloopmanip.c (copy_bbs, record_exit_edges): Removed.
	(scale_bbs_frequencies): Fix comment typo.
	(can_duplicate_loop_p): Use can_copy_bbs_p.
	(duplicate_loop_to_header_edge): Simplify by using copy_bbs.

From-SVN: r68906