Add a quick and dirty script to check validity of links in elf files
Automatically build with debug symbols when building with WITH_CTF.
Otherwise there's nothing for ctfconvert to do, and it ends up emitting an
error for each object file. Also remove some redundant checks from
bsd.prog.mk and bsd.lib.mk.

Differential Revision:	https://reviews.freebsd.org/D1111
Reviewed by:		imp
SUBDIR_DEPENDS__ in lib/Makefile is not working out so well for me.
Add to using _prebuild_libs in (top-level) Makefile.inc1.
NB: Unbreak build yet again (we'll get this right eventually)

Reviewed by:	markj, ngie
Thanks to:	ian, markj, ngie, Nikolai Lifanov <lifanov@mail.lifanov.com>
MFC after:	21 days
X-MFC-to:	stable/10 stable/9
X-MFC-with:	274116 274120 274121 274123 274144 274146 274192
Update the Intel i40e drivers, ixl version 1.2.8, ixlv version 1.1.18
	-Improved VF stability, thanks to changes from Ryan Stone,
	 and Juniper.
	- RSS fixes in the ixlv driver
	- link detection in the ixlv driver
	- New sysctl's added in ixl and ixlv
	- reset timeout increased for ixlv
	- stability fixes in detach
	- correct media reporting
	- Coverity warnings fixed
	- Many small bug fixes
	- VF Makefile modified - nvm shared code needed
	- remove unused sleep channels in ixlv_sc struct

Submitted by: Eric Joyner (committed by jfv)
MFC after:	1 week
Synchronize medium rotation rate in legacy Rigid Disk Drive Geometry mode
page with modern Block Device Characteristics VPD page.

MFC after:	1 week
For really fast machines, an edge-case may exist where dpv(3) may be
built before contrib dependency, dialog(3). Add dialog(3) to the list
of _prebuild_libs to ensure that this does not happen.

Tested on:	11.0-CURRENT amd64 @ r274205
Thanks to:	kargl, Larry Rosenman <ler@lerctr.org>, ngie, markj
Recommended by:	ngie
Reviewed by:	ngie, markj
MFC after:	21 days
X-MFC-to:	stable/10 stable/9
X-MFC-with:	274116 274120 274121 274123 274144 274146 274192 274203
Fix a SIGSEGV when emitting XML or JSON when reading stdin. In that
case the file variable is NULL.
Convert to use libxo.

Obtained from:  Phil Shafer <phil@juniper.net>
Sponsored by:   Juniper Networks, Inc.
Document that df(1) supports libxo(3).
Several minor changes to hopefully complete the VirtIO console driver

  - Support the KDB alt break sequence to enter the debugger,
    panic, reboot, etc. [1]
  - Provide emergency write feature description. Note that QEMU
    does not implement this feature.
  - Make the VTCON_FLAG_* defines sequential once again.
  - When the multiple port feature is not negotiated, query the
    rows and columns of the one console during the device attach
    when the size feature is negotiated.
  - Report failure to the device if hot plugging a port fails.
  - Acknowledge the console port event with an open event. This
    is required by the spec, but QEMU doesn't seem to care.

Submitted by:	Juniper [1]
MFC after:	1 month
Add libxo, now needed by df(1).

Pointed out by: rodrigc@ (thanks!)
Add header file missing from last commit.

Submitted by: jfv
MFC after: 1 week
Merge branch 'master' into markj-develop