Avoid OpenMP/nvptx execution-time hangs for simple nested OpenMP 'target'/'parallel...

Avoid OpenMP/nvptx execution-time hangs for simple nested OpenMP 'target'/'parallel'/'task' constructs [PR99555]

... awaiting proper resolution, of course.

	libgomp/
	PR target/99555
	* testsuite/lib/on_device_arch.c: New file.
	* testsuite/libgomp.c/pr99555-1.c: Likewise.
	* testsuite/libgomp.c-c++-common/task-detach-6.c: Until resolved,
	skip for nvptx offloading, with error status.
	* testsuite/libgomp.fortran/task-detach-6.f90: Likewise.