Ship an amd64 syslinux binary in the ISO

Ship an amd64 syslinux binary in the ISO, otherwise Tails Installer will only work on 32-bit systems.

Feature Branch: feature/9381-ship-amd64-syslinux

Parent Task: #8556 (closed)

Subtasks

• #9609 (closed)

Related issues

• Related to #9421 (closed)
• Related to #9748 (closed)

Original created by @u on 9381 (Redmine)