Given a host, this function will return the user's desired
`rsh'-like command to use to contact that host. This lets the user
choose how to log in on a host-by-host basis. If host is NULL,
then the user's default remote shell command is chosen.
Host where command should be run
Result parameter; number of elements in rsh command
This sets the appropriate options in the config database so that
subsequent calls to gnome_remote_get_command() will return argv.
If host is NULL, then the user's default remote shell is set.
If argc is 0, then this instance of the command is deleted.