This requires to:

1. Copy files around for compatibility between live-build 2.x and syslinux
   3:6.03~pre1+dfsg-1. Ugly, yes.
2. Install isolinux and syslinux-common explicitly, since it is the ones that
   ship isolinux.bin and the *.c32 modules in syslinux 6.x packaging, and are
   merely recommends.