fail in "plabnode alloc" or in the remote vnodesetup call. In the
former case, we do not want to "plabnode free" it later. In the later,
we want to plabnode free it right away, and make sure we do not try to
remote vnode teardown or plabfree it later. In either case, os_setup
needs to check so that it does not bother waiting for the node since
it is wasted time. I use an alternate dead state for this, but the
real solution is to move much of the vnode specific code from os_setup
to vnode_setup.

Note that this stuff is mostly untested since I need nodes to fail!
The normal path works fine though.