Comment 0 for bug 1594871

There are several upstream zfs bug fixes that would be beneficial to sync into zfs utils as a SRU, namely:

Fix user namespaces uid/gid mapping
   commit 874bd959f4f15b3d4b007160ee7ad3f4111dd341
   ZFS #4177

Fix ZPL miswrite of default POSIX ACL
   commit 98f03691a4c08f38ca4538c468e9523f8e6b24be
   ZFS #4520

Create unique partition labels
   commit fbffa53a5cdb9b796de5afc9be8c1f79619253d4
   ZFS #4517

Fix inverted logic on none elevator comparison
   commit 60a4ea3f948f1596b92b666fc7dd21202544edbb
   ZFS #4507

Remove wrong ASSERT in annotate_ecksum
   commit 21ea9460fa880bb072a9ca9d845aef740f9d3af6
   ZFS #4257

Fix 'zpool import' blkid device names
   commit c9ca152fd1de1b0fd959e772b9a25d14a891952b
   ZFS #4523, #3043

Use udev for partition detection
   commit 2cb77346cb698ae0c233c7baf8b4c787205b54e9
   ZFS #4523, #3708, #4077, #4144, #4214, #4517