gdb/gdbserver/

	* server.c (terminal_fd): New variable.
	(old_foreground_pgrp): Likewise.
	(restore_old_foreground_pgrp): New function.
	(start_inferior): Record the terminal file descriptor in terminal_fd
	and its original foreground group in old_foreground_pgrp.  Register
	restore_old_foreground_pgrp with atexit().