re PR middle-end/85874 (gcc points to wrong location when displaying warning for strict overflow warning)

2018-05-23  Richard Biener  <rguenther@suse.de>

	PR middle-end/85874
	* tree-data-ref.c (create_runtime_alias_checks): Defer
	and ignore overflow warnings.

	* gcc.dg/Wstrict-overflow-27.c: New testcase.

From-SVN: r260569