backport: re PR middle-end/86539 (OpenMP wrong-code with taskloop and references)

backport: re PR middle-end/86539 (OpenMP wrong-code with taskloop and references)

	Backported from mainline
	2018-07-17  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/86539
	* gimplify.c (gimplify_omp_for): Ensure taskloop firstprivatized init
	and cond temporaries don't have reference type if iterator has
	pointer type.  For init use &for_pre_body instead of pre_p if
	for_pre_body is non-empty.

	* testsuite/libgomp.c++/pr86539.C: New test.

From-SVN: r265117