Fixed an incorrect gethostname() error message.
Fixed an incorrect gethostname() error message.

On failure, gethostname() sets errno, not h_errno, so use the PLOG macro
to automatically add the failure reason.

Review: https://reviews.apache.org/r/59341/

andschwa/mesos,abudnik/mesos,asamerh4/mesos,Gilbert88/mesos,Gilbert88/mesos,zmalik/mesos,kaysoky/mesos,andschwa/mesos,kaysoky/mesos,abudnik/mesos,gsantovena/mesos,zmalik/mesos,neilconway/mesos,gsantovena/mesos,chhsia0/mesos,neilconway/mesos,dforsyth/mesos,reneploetz/mesos,kaysoky/mesos,andschwa/mesos,Gilbert88/mesos,gsantovena/mesos,chhsia0/mesos,verizonlabs/mesos,abudnik/mesos,dforsyth/mesos,neilconway/mesos,zmalik/mesos,abudnik/mesos,jpeach/mesos,reneploetz/mesos,Gilbert88/mesos,asamerh4/mesos,reneploetz/mesos,kaysoky/mesos,neilconway/mesos,kaysoky/mesos,jpeach/mesos,jpeach/mesos,reneploetz/mesos,reneploetz/mesos,zmalik/mesos,chhsia0/mesos,andschwa/mesos,asamerh4/mesos,verizonlabs/mesos,asamerh4/mesos,kaysoky/mesos,jpeach/mesos,kaysoky/mesos,dforsyth/mesos,dforsyth/mesos,neilconway/mesos,neilconway/mesos,dforsyth/mesos,jpeach/mesos,jpeach/mesos,verizonlabs/mesos,gsantovena/mesos,reneploetz/mesos,asamerh4/mesos,verizonlabs/mesos,chhsia0/mesos,zmalik/mesos,gsantovena/mesos,abudnik/mesos,andschwa/mesos,verizonlabs/mesos,asamerh4/mesos,chhsia0/mesos,andschwa/mesos,zmalik/mesos,Gilbert88/mesos,gsantovena/mesos,Gilbert88/mesos,zmalik/mesos,chhsia0/mesos,reneploetz/mesos,abudnik/mesos,dforsyth/mesos,gsantovena/mesos,dforsyth/mesos,abudnik/mesos,verizonlabs/mesos,andschwa/mesos,neilconway/mesos,asamerh4/mesos,jpeach/mesos,chhsia0/mesos,verizonlabs/mesos,Gilbert88/mesos