Added tests for the new qdisc statistics functions.
Added tests for the new qdisc statistics functions.

Review: https://reviews.apache.org/r/34863

craimbert/mesos,zmalik/mesos,reneploetz/mesos,Aman-Jain-14/customizedMesos,andschwa/mesos,andschwa/mesos,chhsia0/mesos,gsantovena/mesos,gsantovena/mesos,craimbert/mesos,zmalik/mesos,zmalik/mesos,dforsyth/mesos,kaysoky/mesos,reneploetz/mesos,yuquanshan/customizedMesos,gsantovena/mesos,Gilbert88/mesos,asamerh4/mesos,yuquanshan/customizedMesos,kaysoky/mesos,yuquanshan/customizedMesos,Gilbert88/mesos,verizonlabs/mesos,andschwa/mesos,kaysoky/mesos,zmalik/mesos,andschwa/mesos,chhsia0/mesos,dforsyth/mesos,neilconway/mesos,abudnik/mesos,asamerh4/mesos,gsantovena/mesos,abudnik/mesos,asamerh4/mesos,craimbert/mesos,abudnik/mesos,jpeach/mesos,dforsyth/mesos,Gilbert88/mesos,jpeach/mesos,Aman-Jain-14/customizedMesos,Gilbert88/mesos,gsantovena/mesos,abudnik/mesos,andschwa/mesos,neilconway/mesos,reneploetz/mesos,abudnik/mesos,yuquanshan/customizedMesos,chhsia0/mesos,kaysoky/mesos,reneploetz/mesos,verizonlabs/mesos,zmalik/mesos,asamerh4/mesos,andschwa/mesos,neilconway/mesos,dforsyth/mesos,dforsyth/mesos,kaysoky/mesos,zmalik/mesos,neilconway/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,Gilbert88/mesos,chhsia0/mesos,asamerh4/mesos,craimbert/mesos,neilconway/mesos,reneploetz/mesos,jpeach/mesos,Gilbert88/mesos,reneploetz/mesos,verizonlabs/mesos,gsantovena/mesos,asamerh4/mesos,jpeach/mesos,chhsia0/mesos,verizonlabs/mesos,craimbert/mesos,abudnik/mesos,jpeach/mesos,craimbert/mesos,reneploetz/mesos,Aman-Jain-14/customizedMesos,Gilbert88/mesos,neilconway/mesos,dforsyth/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,chhsia0/mesos,verizonlabs/mesos,abudnik/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,jpeach/mesos,verizonlabs/mesos,kaysoky/mesos,zmalik/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,gsantovena/mesos,neilconway/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,craimbert/mesos,jpeach/mesos,yuquanshan/customizedMesos,kaysoky/mesos