Removed a non-existing header from `Makefile.am`.
Removed a non-existing header from `Makefile.am`.

346747e9 included a `stout/thread_local.hpp` which does not exist.

Review: https://reviews.apache.org/r/60110/

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