LU-5435 lnet: lustre network latency simulation

LU-5435 lnet: lustre network latency simulation

Incoming lnet message can be delayed for seconds if it can match
any of LNet Delay Rules.

User can add/remove/list Delay Rule by lctl commands:
- lctl net_delay_add
  Add a new Delay Rule to LNet, options
  <-s | --source SRC_NID>
  <-d | --dest DST_NID>
  <<-r | --rate RATE_NUMBER>
   <-i | --interlval SECONDS>>
  <-l | --latency DELAY_LATENCY>

- lctl net_delay_del
  Remove matched Delay Rule from LNet, options:
  <[-a | --all] |
   <-s | --source SRC_NID>
   <-d | --dest DST_NID>>

- lctl net_delay_list
  List all Delay Rules in LNet

- lctl net_delay_reset
  Reset statistic counters for all Delay Rules

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Change-Id: Iba1234908918ad1619ae85aa2f0ad77a992374aa
Reviewed-on: http://review.whamcloud.com/11409
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>