Add edge predictions pruning

Add edge predictions pruning

	* analyze_brprob.py: Cover new dump output format.
	* predict.c (dump_prediction): Add new argument.
	(enum predictor_reason): New enum.
	(struct predictor_hash): New struct.
	(predictor_hash::hash): New function.
	(predictor_hash::equal): Likewise.
	(not_removed_prediction_p): New function.
	(prune_predictions_for_bb): Likewise.
	(combine_predictions_for_bb): Prune predictions.
	* g++.dg/predict-loop-exit-1.C: Scan for a new dump format.
	* g++.dg/predict-loop-exit-2.C: Likewise.
	* g++.dg/predict-loop-exit-3.C: Likewise.
	* gcc.dg/predict-1.c: Likewise.
	* gcc.dg/predict-2.c: Likewise.
	* gcc.dg/predict-3.c: Likewise.
	* gcc.dg/predict-4.c: Likewise.
	* gcc.dg/predict-5.c: Likewise.
	* gcc.dg/predict-6.c: Likewise.
	* gcc.dg/predict-7.c: Likewise.

From-SVN: r237255