compat: backport FQ CoDel support down to 2.6.25

compat: backport FQ CoDel support down to 2.6.25

FQ CoDel is available as a module, sch_fq_codel.

This backports:

commit 4b549a2ef4bef9965d97cbd992ba67930cd3e0fe
Author: Eric Dumazet <edumazet@google.com>
Date:   Fri May 11 09:30:50 2012 +0000

    fq_codel: Fair Queue Codel AQM

    Fair Queue Codel packet scheduler

    Principles :

    - Packets are classified (internal classifier or external) on flows.
    - This is a Stochastic model (as we use a hash, several flows might
                                  be hashed on same slot)
    - Each flow has a CoDel managed queue.
    - Flows are linked onto two (Round Robin) lists,
      so that new flows have priority on old ones.

    - For a given flow, packets are not reordered (CoDel uses a FIFO)
    - head drops only.
    - ECN capability is on by default.
    - Very low memory footprint (64 bytes per flow)

I should note that this is different than CoDel. This code is GPL,
CoDel is Dual BSD/GPL licensed. This goes only compile tested against
all the below kernels, run time test results would be appreciated.

mcgrof@tux ~/compat (git::master)$ ckmake
Trying kernel                  3.4.0-030400rc1-generic  [OK]
Trying kernel                     3.3.7-030307-generic  [OK]
Trying kernel                     3.2.2-030202-generic  [OK]
Trying kernel                    3.1.10-030110-generic  [OK]
Trying kernel                    3.0.18-030018-generic  [OK]
Trying kernel                  2.6.39-02063904-generic  [OK]
Trying kernel                  2.6.38-02063808-generic  [OK]
Trying kernel                  2.6.37-02063706-generic  [OK]
Trying kernel                  2.6.36-02063604-generic  [OK]
Trying kernel                  2.6.35-02063512-generic  [OK]
Trying kernel                  2.6.34-02063410-generic  [OK]
Trying kernel                  2.6.33-02063305-generic  [OK]
Trying kernel                  2.6.32-02063255-generic  [OK]
Trying kernel                  2.6.31-02063113-generic  [OK]
Trying kernel                  2.6.30-02063010-generic  [OK]
Trying kernel                  2.6.29-02062906-generic  [OK]
Trying kernel                  2.6.28-02062810-generic  [OK]
Trying kernel                    2.6.27-020627-generic  [OK]
Trying kernel                    2.6.26-020626-generic  [OK]
Trying kernel                    2.6.25-020625-generic  [OK]
Trying kernel                    2.6.24-020624-generic  [OK]

Signed-off-by: Luis R. Rodriguez <mcgrof@frijolero.org>