Used `size_t` instead of `int` to track number of frameworks per role.
Used `size_t` instead of `int` to track number of frameworks per role.

Per informal project style, we prefer using `size_t` when representing
a count or the size of a collection.

Review: https://reviews.apache.org/r/43848/

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