* predict.c (return_prediction): New function.
	(apply_return_prediction): Likewise.
	(tree_bb_level_predictions): Likewise.
	(tree_estimate_probability): Add noreturn exit edges; call
	bb_level_predictions; fix logic of return heuristics.
	(predict_paths_leading_to):  Rescuesce from old CVS version of
	process_note_prediction function.
	* predict.def (PRED_TREE_EARLY_RETURN): New predictor.

From-SVN: r87768