Make more compiler warnings into errors
Make more compiler warnings into errors

In particular, I want -Werror=format=2 to catch format string bugs.

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