gitignore: Add ostree-prepare-root and ostree-remount binaries
gitignore: Add ostree-prepare-root and ostree-remount binaries

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