Fixes for profile count/probability maintenance

Verifier checks have recently been strengthened to check that
all counts and probabilities are initialized. The checks fired
during autoprofiledbootstrap build and this patch fixes it.

Tested on x86_64-pc-linux-gnu.

gcc/ChangeLog:
	* auto-profile.cc (afdo_calculate_branch_prob): Fix count comparisons
	* tree-vect-loop-manip.cc (vect_do_peeling): Guard against zero count
	when scaling loop profile