MFC r287009, r287120 and r298131:

Add ALTQ(9) support for the CoDel algorithm.

CoDel is a parameterless queue discipline that handles variable bandwidth
and RTT.

It can be used as the single queue discipline on an interface or as a sub
discipline of existing queue disciplines such as PRIQ, CBQ, HFSC, FAIRQ.

Obtained from: pfSense
Sponsored by: Rubicon Communications (Netgate)

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

This commit was generated by cvs2svn to compensate for changes in r130365,
which included commits to RCS files with non-trunk default branches.

Import parts of the ALTQ framework from latest KAME snapshot (which is up to
HEAD at this point). This will not exactly live in a vendor branch, but have
the vendor backing to make it easier to exchange diffs.

This will be followed by a diff which takes most of the .c files off the
vendor branch in order to:
- add locking
- disable ALTQ3_COMPAT code (which is outdated and "un-lockable")

There is work in progress to refine the configuration API. Import this "as
is" now to have more exposure time before 5-STABLE.

This is only the import, it will be some more days until you will actually
be able to compile ALTQ support into your kernel so don't hold your breath.
HEADUPs will be posted on current@ and net@ before this is actually enabled.

No-objection: re(scottl), core(rwatson)