MFC r311572, r311895, r311928, r311985, r312395, r312417

r311572:
Fix file descriptor leaks in cmp(1)

Also, add a few test cases

Reported by: Coverity
CID: 271624 275338
Reviewed by: ngie
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D9074

r311895:
Fix memory leaks during "tail -r" of an irregular file

* Rewrite r_buf to use standard tail queues instead of a hand-rolled
circular linked list. Free dynamic allocations when done.
* Remove an optimization for the case where the file is a multiple of 128KB
in size and there is a scarcity of memory.
* Add ATF tests for "tail -r" and its variants.

Reported by: Valgrind
Reviewed by: ngie
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D9067

r311928:
Fix build of usr.bin/tail with GCC

Submitted by: pluknet
Reported by: pluknet
MFC after: 27 days
X-MFC-with: 311895
Sponsored by: Spectra Logic Corp

r311985:
Fix uninitialized variable CIDs in route6d

The variables in question are actually return arguments, but it's still good
form to initialize them.

Reported by: Coverity
CID: 979679 979680
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

r312395:
Fix several Coverity CIDs in devd

CID 1362055, 1362054: File descriptor leaks during shutdown
CID 1362013: Potential null-termination fail with long network device names
CID 1362097: Uncaught exception during memory pressure
CID 1362017, 1362016: Unchecked errors, possibly resulting in weird behavior
if two devd instances start at the same time.
CID 1362015: Unchecked error that will probably never fail

Reported by: Coverity
CID: 1362055 1362054 1362013 1362097 1362017 1362016 1362015
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp

r312417:
Fix build of devd with GCC 4.2

Reported by: olivier
Pointy-hat-to: asomers
MFC after: 27 days
X-MFC-with: 312395
Sponsored by: Spectra Logic Corp

MFC r311711,r311712,r311713:

r311711:

Clean up trailing whitespace

r311712:

Sort #includes

r311713:

Use nitems(mib) instead of hardcoding mib's length

MFC r299491:
r299491 (by cem):

route6d(8): Fix potential double-free

In the case that the subsequent sysctl(3) call failed, 'buf' could be free(3)ed
repeatedly. It isn't clear to me that that case is possible, but be clear and
do the right thing in case it is.

CID: 272537

MFC r299869

Use strlcpy() instead of strncpy() when copying ifname to ensure
that it is NUL terminated. Additional NUL padding is not required
for short names.

Reported by: Coverity
CID: 1009974

MFC r270234:

Recover sin6_scope_id of gateway addresses in riprecv() by using the if_index
where a RIP packet was received. This fixes a bug which prevented gateway
addresses in fe80::/64 from being added.

Merge r263203: garbage collect long time obsoleted (or never used) stuff
from routing API.

Merge r263658 from head: remove unneeded fake _KERNEL definition.
Should fix broken builds.

MFC r270234:

Recover sin6_scope_id of gateway addresses in riprecv() by using the if_index
where a RIP packet was received. This fixes a bug which prevented gateway
addresses in fe80::/64 from being added.

Merge r263203: garbage collect long time obsoleted (or never used) stuff
from routing API.

Merge r263658 from head: remove unneeded fake _KERNEL definition.
Should fix broken builds.