Merge from NetBSD from 1999-03-25:"
 * don't close the socket unless it was opened by the function
 * note (in the comments) that the client is responsible for closing
  the socket if they opened it, or they didn't use CLNT_DESTROY()

  fixes a couple of unnecessary closing of already-closed sockets.
  noted by: Matthias Drochner <M.Drochner@fz-juelich.de>"

tested by many in snaps
ok schwarze@