backport: re PR c/81687 (Compiler drops label in OpenMP region)

backport: re PR c/81687 (Compiler drops label in OpenMP region)

	Backported from mainline
	2017-08-09  Jakub Jelinek  <jakub@redhat.com>

	PR c/81687
	* omp-low.c (omp_copy_decl): Don't remap FORCED_LABEL or DECL_NONLOCAL
	LABEL_DECLs.
	* tree-cfg.c (move_stmt_op): Don't adjust DECL_CONTEXT of FORCED_LABEL
	or DECL_NONLOCAL labels.
	(move_stmt_r) <case GIMPLE_LABEL>: Adjust DECL_CONTEXT of FORCED_LABEL
	or DECL_NONLOCAL labels here.

	* testsuite/libgomp.c/pr81687-1.c: New test.
	* testsuite/libgomp.c/pr81687-2.c: New test.

From-SVN: r252885