MFV r275914:

As of r270383, the dbuf_compare comparator compares the dbuf
attributes in the following order:

	db_level (indirect level)
	db_blkid (block number)
	db_state (current state)
	the address of the element

Because db_state is being considered before the element's state,
changing of db_state would affect balancedness of the AVL tree,
even when the address of element compares differently.  For
instance, in dbuf_create, db_state may be altered after the
node is inserted into the AVL tree and may break AVL tree
balancedness.

Instead of using db_state as a comparision critera (introduced
in r270383), consider it only when we are doing a lookup, that
is one of the two dbuf pointers contains DB_SEARCH.

Illumos issue:
    5422 preserve AVL invariants in dn_dbufs

MFC after:	2 weeks
Add missing continue: we can't proceed further if the
kernel does not panic with zfs_panic_recover.

Illumos issue:
    5438 zfs_blkptr_verify should continue after zfs_panic_recover

Reported by:	Coverity
CID:		1232014
Slightly polish iSCSI parameters negotiation.

MFC after:	1 week
Make ieee80211_add_ssid() public.

Some drivers use private copies of this.

PR:		kern/196116
Submitted by:	Andriy Voskoboinyk <s3erios@gmail.com>
Remove a private copy of ieee80211_add_ssid().

PR:		kern/196116
Submitted by:	Andriy Voskoboinyk <s3erios@gmail.com>
Merge remote-tracking branch 'freebsd/master' into hardened/current/master