deploy: fsync() copy of /etc
deploy: fsync() copy of /etc

This unfortunately requires reimplementing gs_shutil_cp_a(), except
while we're here, we also use the *at calls.

leandrosansilva/ostree,leandrosansilva/ostree,gatispaeglis/ostree,resin-io/ostree,sujitfulse/ostree,sujitfulse/ostree,gatispaeglis/ostree,sujitfulse/ostree,gatispaeglis/ostree,GNOME/ostree,sujitfulse/ostree,gatispaeglis/ostree,resin-io/ostree,leandrosansilva/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,GNOME/ostree,leandrosansilva/ostree,leandrosansilva/ostree,GNOME/ostree,resin-io/ostree,resin-io/ostree,GNOME/ostree,sujitfulse/ostree,resin-io/ostree