Add libexecinfo Makefile

Sponsored by:	DARPA, AFRL
- Bump date.
- Small mdoc fix.

Submitted by:	pluknet
zfs: inline and remove zfs_vnode_lock

It didn't serve any useful purpose, but obscured file and line information
useful for debugging.

MFC after:	5 days
X-MFC with:	r254445
Fix the build and fix style.

Pointy-hat to:	davide
fbt: drop a local write-only variable

Discovered with:	gcc46
MFC after:	4 days
zfs: do not reject any operations on a pool just because it's a boot pool

Unlike the upstream FreeBSD supports booting to all kinds of pools.

Requested by:	many
Tested by:	sbruno
MFC after:	12 days
Since the 253927, which removed the soft busy call for the sf page, it
does not make sense to wait for the soft busy state of the page to
drain.  The vm object lock is dropped immediately after, so the result
of the wait is invalidated.

It might make sense to not wait for the hard busy state as well,
esp. for the fully valid page, but this is postponed for now.

Reviewed by:	alc
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Don't give up so easily on failure of CMD55 to put the card into app-cmd
mode.  We don't know why it failed, so we can't know that a retry will
also fail (the low-level driver might have reset the controller state
machine or something similar that would allow a retry to work).