Cleaned up the utility structs in the allocator.
Cleaned up the utility structs in the allocator.

Review: https://reviews.apache.org/r/28663

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