Windows: Fixed subprocess and setsid compilation errors.
Windows: Fixed subprocess and setsid compilation errors.

This changes the `ChildHook::SETSID` to a noop on Windows
as there is no equivalent functionality on this OS.

By default, the lifetime of child processes on Windows are not
tied to the parent process (`setsid()` on Posix prevents child
processes from dying when the parent dies).

Review: https://reviews.apache.org/r/52129/

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