Bring over illumos ZFS FMA logic -- phase 1

This first phase brings over the ZFS SLM module, zfs_mod.c, to handle
auto operations in response to disk events. Disk event monitoring is
provided from libudev and generates the expected payload schema for
zfs_mod. This work leverages the recently added devid and phys_path
strings in the vdev label.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Don Brady <don.brady@intel.com>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #4673

cmd/zed/agents/zfs_retire.c

@@ -0,0 +1,45 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
+ */
+
+#include "zfs_agents.h"
+#include "../zed_log.h"
+
+/*ARGSUSED*/
+void
+zfs_retire_recv(nvlist_t *nvl, const char *class)
+{
+}
+
+/*ARGSUSED*/
+int
+zfs_retire_init(libzfs_handle_t *zfs_hdl)
+{
+	return (0);
+}
+
+/*ARGSUSED*/
+void
+zfs_retire_fini(void)
+{
+}