Minor fix for libev-unbundled in python setup.
Minor fix for libev-unbundled in python setup.

Review: https://reviews.apache.org/r/23785

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