A deadlock in the NFSv4 server with vfs.nfsd.enable_locallocks=1
was reported via email. This was caused by a LOR between the
sleep lock used to serialize the local locking (nfsrv_locklf())
and locking the vnode. I believe this patch fixes the problem
by delaying relocking of the vnode until the sleep lock is
unlocked (nfsrv_unlocklf()). To avoid nfsvno_advlock() having the side
effect of unlocking the vnode, unlocking the vnode was moved to before
the functions that call nfsvno_advlock().
It shouldn't affect the execution of the default case where
vfs.nfsd.enable_locallocks=0.

Reported by:	loic.blot@unix-experience.fr
Discussed with:	kib
MFC after:	1 week
Prevent zpool upgrade failing due to unavailable pools

Prior to this fix "zpool upgrade" and "zpool upgrade -a" would fail due to
an assert when operating on unavailable pools.

We now print a warning to stderr but allow the processing of other pools
to procesed.

MFC after:	1 month
Move libxo to /lib

Update ObsoleteFiles to reflect libxo move.

Reviewed by: ngie
Differential Revision: https://reviews.freebsd.org/D1370
Change the style of the DO_AST macro to match the others in this file --
semicolons between the code and comments instead of after the comments,
and line continuations in the arbitrary but now consistant column 76.

No functional changes.
Oops, I fumbled a semicolon on the style changes; recover it.
Remove _PROF_PROLOGUE from the EENTRY() macros.  These macros define
'extra' entry points which are nested within or provide a synonym name
for another function.  It's most likely not safe to be messing with the
IP and LR registers at anything other than the primary entry point to a
function.  Anywhere beyond initial function entry, those registers may
be in use as scratch or variable registers.
Merge remote-tracking branch 'freebsd/master' into hardened/current/master