PR sanitizer/83987
	* omp-low.c (maybe_remove_omp_member_access_dummy_vars,
	remove_member_access_dummy_vars): New functions.
	(lower_omp_for, lower_omp_taskreg, lower_omp_target,
	lower_omp_1, execute_lower_omp): Use them.

	* tree.c (cp_free_lang_data): Revert 2018-01-23 change.

	* g++.dg/ubsan/pr83987-2.C: New test.

From-SVN: r257545