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)