re PR c/41673 (variable-length array dereference inside sizeof gives "warning: dereferencing type-punned pointer will break strict-aliasing rules")

	PR c/41673
	* alias.c (get_alias_set): Call langhook before returning 0 for
	types with structural equality.
	* c-common.c (c_common_get_alias_set): Use alias set of element
	type for arrays with structural comparison.

testsuite:
	* gcc.dg/Wstrict-aliasing-bogus-vla-1.c: New test.

From-SVN: r153496