Removed requirement for GTESTS to use their own tuple in libprocess.
Removed requirement for GTESTS to use their own tuple in libprocess.

Review: https://reviews.apache.org/r/18852

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