[Cake] [PATCH 1/3] pkt_sched.h: add support for sch_cake API

[Dave Taht]

If we are going to open up the xstats API discussion, it might be helpful
to look at some examples of current output. If at some future time we
wanted more tins than 8, even fitting 3 tins pm tje screen still has
issues.

Another option for all these extended statistics is to toss them in sysfs.
/me hides

qdisc cake 8010: dev enp3s0 root refcnt 2 bandwidth 10Mbit diffserv3
triple-isolate ack-filter rtt 100.0ms raw total_overhead 14
hard_header_len 14
 Sent 78231606 bytes 364051 pkt (dropped 5, overlimits 910781 requeues 0)
## dropped stats appears to be wrong presently, should include ack_drops

 backlog 0b 0p requeues 0
 memory used: 117696b of 4Mb
 capacity estimate: 10Mbit
                 Bulk   Best Effort      Voice
  thresh       625Kbit      10Mbit    2500Kbit
  target        29.1ms       5.0ms       7.3ms
  interval     124.1ms     100.0ms      14.5ms
  pk_delay         0us       279us       4.9ms
  av_delay         0us        15us       182us
  sp_delay         0us         7us         4us
  pkts               0      369415         111
  bytes              0    78568833       24475
  way_inds           0           0           0
  way_miss           0          42           3
  way_cols           0           0           0
  drops              0           4           1
  marks              0       39346           0
  ack_drop           0        5470           0
  sp_flows           0           1           0
  bk_flows           0           0           1
  un_flows           0           0           0
  max_len            0        3028        1267