Make libgomp respect the on device offset of subarrays which may arise in
present data clauses.

	libgomp/
	PR libgomp/88288
	* oacc-parallel.c (GOACC_parallel_keyed): Add offset to devaddrs.
	* testsuite/libgomp.oacc-c-c++-common/pr88288.c: New test.

Reviewed-by: Thomas Schwinge <thomas@codesourcery.com>

From-SVN: r266688