Dealt with some type casting warnings in common/values.cpp.
Dealt with some type casting warnings in common/values.cpp.

This fixes the type of the local variable we use to store an
IO stream's original precision while outputing a `Scalar` value.
We extraneously cast from a `std::streamsize` (`int`) to `long`.

Also, this removes an extranous cast from `size_t` to `int` in
a vector iteration loop.

Review: https://reviews.apache.org/r/56675/

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