Introduce PROB_UNINITIALIZED constant and use it in predict.def.

Introduce PROB_UNINITIALIZED constant and use it in predict.def.

2018-01-19  Martin Liska  <mliska@suse.cz>

	* predict.c (predict_insn_def): Add new assert.
	(struct branch_predictor): Change type to signed integer.
	(test_prediction_value_range): Amend test to cover
	PROB_UNINITIALIZED.
	* predict.def (PRED_LOOP_ITERATIONS): Use the new constant.
	(PRED_LOOP_ITERATIONS_GUESSED): Likewise.
	(PRED_LOOP_ITERATIONS_MAX): Likewise.
	(PRED_LOOP_IV_COMPARE): Likewise.
	* predict.h (PROB_UNINITIALIZED): Define new constant.

From-SVN: r256887