Move postfold_gcond_edges into fur_source.

The code registering outgoing edges from a cond is living in
fold_using_range, which makes it difficult to be called from other
places.  Also, it refuses to register relations on the outgoing
destinations that have more than one predecessor.  This latter issue is
a problem because we would like to register outgoing edges along a path
in the path solver (regardless of single_pred_p).

gcc/ChangeLog:

	* gimple-range-fold.cc (fold_using_range::range_of_range_op):
	Rename postfold_gcond_edges to register_outgoing_edges and
	adapt.
	(fold_using_range::postfold_gcond_edges): Rename...
	(fur_source::register_outgoing_edges): ...to this.
	* gimple-range-fold.h (postfold_gcond_edges): Rename to
	register_outgoing_edges and move to fur_source.
2 files changed