change inverted_post_order_compute to inverted_rev_post_order_compute

change inverted_post_order_compute to inverted_rev_post_order_compute

The following changes the inverted_post_order_compute API back to
a plain C array interface and computing a reverse post order since
that's what's always required.  It will make massaging DF to use
the correct iteration orders easier.  Elsewhere it requires turning
backward iteration over the computed order with forward iteration.

	* cfganal.h (inverted_rev_post_order_compute): Rename
	from ...
	(inverted_post_order_compute): ... this.  Add struct function
	argument, change allocation to a C array.
	* cfganal.cc (inverted_rev_post_order_compute): Likewise.
	* lcm.cc (compute_antinout_edge): Adjust.
	* lra-lives.cc (lra_create_live_ranges_1): Likewise.
	* tree-ssa-dce.cc (remove_dead_stmt): Likewise.
	* tree-ssa-pre.cc (compute_antic): Likewise.