This achieves two things:
- Programs can now intentionally perform arbitrary syscalls by calling
syscall(). This allows us to work on things like syscall fuzzing.
- It restricts the ability of userspace to make syscalls to a single
4KB page of code. In order to call the kernel directly, an attacker
must now locate this page and call through it.
Because it was 'static const' and also shared with userland programs,
the default keymap was defined in multiple places. This commit should
save several kilobytes! :^)
