* linux-low.c (linux_create_inferior): Call setpgid. Return

    * linux-low.c (linux_create_inferior): Call setpgid.  Return
        the new PID.
        (unstopped_p, linux_signal_pid): Remove.
        (linux_target_ops): Remove linux_signal_pid.
        * remote-utils.c (putpkt, input_interrupt): Use signal_pid
        global instead of target method.
        * target.h (struct target_ops): Remove signal_pid.  Update comment
        for create_inferior.
        * server.c (signal_pid): New variable.
        (create_inferior): Set signal_pid.  Block SIGTTOU and SIGTTIN in
        gdbserver.  Set the child to be the foreground process group.
        (attach_inferior): Set signal_pid.