OpenBSD / NetBSD: open_files()'s path is always empty

[giampaolo]

Contrarily from FreeBSD it appears OpenBSD / NetBSD do not save the path in the kinfo_file struct:

psutil/psutil/_psutil_bsd.c

Lines 488 to 503 in 5e543ef

	#ifdef PSUTIL_FREEBSD
	if ((kif->kf_type == KF_TYPE_VNODE) &&
	(kif->kf_vnode_type == KF_VTYPE_VREG))
	{
	py_tuple = Py_BuildValue("(si)", kif->kf_path, kif->kf_fd);
	#elif PSUTIL_OPENBSD
	if ((kif->f_type == DTYPE_VNODE) &&
	(kif->v_type == VREG))
	{
	py_tuple = Py_BuildValue("(si)", "", kif->fd_fd);
	#elif PSUTIL_NETBSD
	if ((kif->ki_ftype == DTYPE_VNODE) &&
	(kif->ki_vtype == VREG))
	{
	py_tuple = Py_BuildValue("(si)", "", kif->ki_fd);
	#endif

....which makes the method completely useless (well except for file ids...).
Filing this ticket as a reminder to look into whether I've missed something but if paths can't be determined this shall me removed.

[giampaolo]

Also, in case of removal this should be resolved before 5.3.0 so that we can break backward compatibility.