MFC r266941, r266955

Needed for anticipated dummynet AQM MFC next week.

r266941 | hiren | 2014-06-01 00:28:24 -0700 (Sun, 01 Jun 2014) | 9 lines

ECN marking implenetation for dummynet.
Changes include both DCTCP and RFC 3168 ECN marking methodology.

DCTCP draft: http://tools.ietf.org/html/draft-bensley-tcpm-dctcp-00

Submitted by: Midori Kato (aoimidori27@gmail.com)
Worked with: Lars Eggert (lars@netapp.com)
Reviewed by: luigi, hiren

r266955 | hiren | 2014-06-01 13:19:17 -0700 (Sun, 01 Jun 2014) | 5 lines

DNOLD_IS_ECN introduced by r266941 is not required.
DNOLD_* flags are for compat with old binaries.

Suggested by: luigi

Discussed with: hiren
Relnotes: yes