Call infer_non_null() directly when checking for non-null.

Call infer_non_null() directly when checking for non-null.

Simply call infer_non_null directly and avoid uneccessary checks of
the statement being modified.

	gcc/
	PR tree-optimization/97609
	* gimple-range-cache.cc (non_null_ref::process_name): Call
	infer_nonnull_range directly instead of infer_value_range.
	gcc/testsuite/
	* g++.dg/pr97609.C: New.