lib: Port to g_memdup2
lib: Port to g_memdup2

See https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538

GNOME/gnome-characters,GNOME/gnome-characters,GNOME/gnome-characters,GNOME/gnome-characters,GNOME/gnome-characters