MFV r253781 + r253871:

Illumos ZFS issues:
  3894 zfs should not allow snapshot of inconsistent dataset

MFC after:	2 weeks

(cherry picked from commit c5affee6a3a59d69c44d3493fa98bec9080bb11f)
MFV r253782:

To quote Illumos issue #3888:

When 'zfs recv -F' is used with an incremental recv it rolls
back any changes made since the last snapshot in case new
changes were made to the file system while the recv is in
progress (without -F the recv would fail when it does it's
final check to commit the recv-ed data as the recv-ed data
conflicts with the newly written data).

However, if there is a snapshot taken after the recv began
rolling back to the 'latest' snapshot will not help and the
recv will still fail. 'zfs recv -F' should be extended to
destroy any snapshots created since the source snapshot when
finishing the recv (effectively rolling back through all
snapshots, instead of just to the latest snapshot).

Illumos ZFS issues:
  3888 zfs recv -F should destroy any snapshots created since the
       incremental source

MFC after:	2 weeks

(cherry picked from commit 6cd9d0f4540cebd88fc799aa2cb692e8d3d49dcd)
MFV r264829:

3897 zfs filesystem and snapshot limits

MFC after:	2 weeks

(cherry picked from commit 4a1b97c2c074b95c815a8d7596b8858e2b7e3177)
MFV r264830:

4745 fix AVL code misspellings

MFC after:	2 weeks

(cherry picked from commit 4d48e09fd736c5e6c154af2a2c4af1557f6a17ad)