Improved performance of 'roles::validate'.
Improved performance of 'roles::validate'.

This validation is used inside resource math which in turn is used
heavily in the code base.
The temporary string allocations caused a significant performance
degradation in this critical path.

Review: https://reviews.apache.org/r/42762

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