Fix PR 108980: note without warning due to array bounds check

The problem here is after r13-4748-g2a27ae32fabf85, in some
cases we were calling inform without a corresponding warning.
This changes the logic such that we only cause that to happen
if there was a warning happened before hand.

Changes since
* v1: Fix formating and dump message as suggested by Jakub.

OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	PR tree-optimization/108980
	* gimple-array-bounds.cc (array_bounds_checker::check_array_ref):
	Reorgnize the call to warning for not strict flexible arrays
	to be before the check of warned.