Add -B option to have exports_setup only generate boss-side mount list.
Add -B option to have exports_setup only generate boss-side mount list.

This is needed in the WITHZFS && !WITHAMD case where ZFS handles the
HUPing of mountd but we still need to generate the valid mount list
for autofs on boss.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome