hdt in boot menu requires it:
| Failed to load libmenu.c32
| Failed to load COM32 file /boot/addons/hdt.c32
copy_addon_file ifcpu64.c32 /usr/lib/syslinux/modules/bios/ isolinux
copy_addon_file ldlinux.c32 /usr/lib/syslinux/modules/bios/ isolinux
copy_addon_file libcom32.c32 /usr/lib/syslinux/modules/bios/ isolinux
+ copy_addon_file libmenu.c32 /usr/lib/syslinux/modules/bios/ isolinux
copy_addon_file libutil.c32 /usr/lib/syslinux/modules/bios/ isolinux
copy_addon_file vesamenu.c32 /usr/lib/syslinux/modules/bios/ isolinux
else # syslinux versions <= 3:4.05+dfsg-6+deb8u1