re PR libgomp/69555 (libgomp.c++/target-6.C fails because of undefined behaviour)

	PR libgomp/69555
	* gimplify.c (gimplify_decl_expr): For decls with REFERENCE_TYPE, also
	gimplify_type_sizes the type they refer to.
	(omp_notice_variable): Handle reference vars to VLAs.
	* omp-low.c (lower_omp_target): Emit setup of OMP_CLAUSE_PRIVATE reference
	to VLA decls in the second pass instead of first pass.

	* testsuite/libgomp.c++/pr69555-1.C: New test.
	* testsuite/libgomp.c++/pr69555-2.C: New test.

From-SVN: r233913