Retire zpool_id infrastructure

In the interest of maintaining only one udev helper to give vdevs
user friendly names, the zpool_id and zpool_layout infrastructure
is being retired.  They are superseded by vdev_id which incorporates
all the previous functionality.

Documentation for the new vdev_id(8) helper and its configuration
file, vdev_id.conf(5), can be found in their respective man pages.
Several useful example files are installed under /etc/zfs/.

  /etc/zfs/vdev_id.conf.alias.example
  /etc/zfs/vdev_id.conf.multipath.example
  /etc/zfs/vdev_id.conf.sas_direct.example
  /etc/zfs/vdev_id.conf.sas_switch.example

Signed-off-by: Brian Behlendorf <[email protected]>
Closes openzfs#981

PKGBUILD-zfs.in

@@ -7,7 +7,6 @@ arch=(x86_64)
 url="git://github.com/zfsonlinux/zfs.git"
 license=(@ZFS_META_LICENSE@)
 depends=('spl' 'zlib' 'e2fsprogs')
-backup=('etc/zfs/zdev.conf')
 source=(@ZFS_META_NAME@-@[email protected])
 
 build() {

cmd/Makefile.am

@@ -1,2 +1,2 @@
 SUBDIRS  = zfs zpool zdb zhack zinject zstreamdump ztest zpios
-SUBDIRS += mount_zfs fsck_zfs zpool_layout zvol_id zpool_id vdev_id
+SUBDIRS += mount_zfs fsck_zfs zvol_id vdev_id