generator: Use g_ascii_dtostr() to avoid losing precision
generator: Use g_ascii_dtostr() to avoid losing precision

The nice format escape for g_ascii_formatd() is not really suited for a
serialization format, as it obviously loses precision.

https://bugzilla.gnome.org/show_bug.cgi?id=637244

frida/json-glib,robtaylor/json-glib-gvariant,Distrotech/json-glib,GNOME/json-glib,oerdnj/json-glib,brauliobo/json-glib,robtaylor/json-glib-gvariant,ebassi/json-glib,oerdnj/json-glib,Distrotech/json-glib,GNOME/json-glib,frida/json-glib,oerdnj/json-glib,ebassi/json-glib,Distrotech/json-glib,brauliobo/json-glib,brauliobo/json-glib,oerdnj/json-glib,ebassi/json-glib