instead of it being always provided by the rump kernel base. This
move accomplishes two things:
1) it is no longer necessary to provide sysproxy hypercall stubs for
platforms which do not want to use sysproxy
2) it is easier to reason about the security aspects, since configurations
not linking the sysproxy component simply do not support remote
system calls
discussed on rumpkernel-users
This enables us to remove custom Atffiles whose only purpose was to avoid
using the helpers as tests.
XXX src/tests/dev/dm/ is not (yet) linked into the build!
Notably, md is a little tricky for this, since the ioctl that
configures the service also blocks in the kernel. Therefore, use
an additional pthread to probe when the service is fully configured
and the server can detach.
Also, rawpart love.
