po: Add utilities to the POTFILES
po: Add utilities to the POTFILES

They come with translatable strings.

GNOME/json-glib,Distrotech/json-glib,ebassi/json-glib,Distrotech/json-glib,ebassi/json-glib,ebassi/json-glib,Distrotech/json-glib,GNOME/json-glib,frida/json-glib,frida/json-glib