- use negative errnos in repl addrq/delrq because that is what the RPC   layer expects - prevent removal of last replica.  i am shocked this code didn't exist.   pointed out by kheilman@
- use negative errnos in repl addrq/delrq because that is what the RPC
  layer expects
- prevent removal of last replica.  i am shocked this code didn't exist.
  pointed out by kheilman@


git-svn-id: ae92b08b608af1c8cefa3e10d2325ea527204e07@19352 3eda493b-6a19-0410-b2e0-ec8ea4dd8fda

pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable