Root the lib32 object tree under the overall object tree.

This enables a common root directory for all object files for a given tree,
which eases sharing a common MAKEOBJDIRPREFIX, and cleaning up of object trees.

In particular, one can simply (from the source directory) rm -rf /usr/obj$(pwd)
to destroy all object files for it.  Or to copy/sync files, etc.

Reviewed by:	bdrewery
CR:		https://reviews.freebsd.org/D796
MFC after:	1 month
Sponsored by:	Spectra Logic
Fix a kernel panic when unloading isp(4).

In the current implementation, the isp_kthread() threads never exit.

The target threads do have an exit mode from isp_attach(), but it is
not invoked from isp_detach().

Ensure isp_detach() notifies threads started for each channel, such
that they exit before their parent device softc detaches, and thus
before the module does.  Otherwise, a page fault panic occurs later in:

sysctl_kern_proc
  sysctl_out_proc
    kern_proc_out
      fill_kinfo_proc
        fill_kinfo_thread
          strlcpy(kp->ki_wmesg, td->td_wmesg, sizeof(kp->ki_wmesg));

For isp_kthread() (and isp(4) target threads), td->td_wmesg references
now-unmapped memory after the module has been unloaded.  These threads
are typically msleep()ing at the time of unload, but they could also
attempt to execute now-unmapped code segments.

MFC after:	1 month
Sponsored by:	Spectra Logic
MFSpectraBSD:	r1070921 on 2014/06/22 13:01:17
Add laggproto broadcast, it allows sends frames to all ports of the lagg(4) group
and receives frames on any port of the lagg(4).

Phabric:	D549
Reviewed by:	glebius, thompsa
Approved by:	glebius
Obtained from:	OpenBSD
Sponsored by:	QNAP Systems Inc.