[$] Enforcement (or not) for module-specific exported symbols

Loadable kernel modules require access to kernel data structures and
functions to get their job done; the kernel provides this access by way of
exported symbols. Almost since this mechanism was created, there have been
debates over which symbols should be exported, and how. The 6.16 kernel
gained a new export mechanism that limits access to symbols to specific
kernel modules. That code is likely to change soon, but the addition
of an enforcement mechanism has since been backed out.