re PR tree-optimization/83081 ([arm] gcc.dg/pr80218.c fails since r254888)

re PR tree-optimization/83081 ([arm] gcc.dg/pr80218.c fails since r254888)

	PR tree-optimization/83081
	* profile-count.h (profile_probability::split): New method.
	* dojump.c (do_jump_1) <case TRUTH_ANDIF_EXPR, case TRUTH_ORIF_EXPR>:
	Use profile_probability::split.
	(do_compare_rtx_and_jump): Fix adjustment of probabilities
	when splitting a single conditional jump into 2.

	* gcc.dg/predict-8.c: Adjust expected probability.

From-SVN: r256966