At least the apache sever is very unhappy with that extra null line and will
take more than ten seconds in responding to each range request, which slows
down a lot the entire http file transfer process or even time out.

	* grub-core/net/http.c (parse_line): Handle response 206.
	(http_receive): Stall if too many packets are in the queue.
	(http_establish): Fix range header.
	(http_seek): Fix double free.
	(http_close): Likewise.
	(http_packets_pulled): New function.
	(grub_http_protocol): Set http_seek
	* grub-core/net/tcp.c (grub_net_tcp_socket): New field `i_stall'.
	(ack_real): Set window depending on i_stall.
	(grub_net_send_tcp_packet): Likewise.
	(grub_net_tcp_stall): New function.
	(grub_net_tcp_unstall): Likewise.
	* include/grub/net/tcp.h (grub_net_tcp_stall): New proto.
	(grub_net_tcp_unstall): Likewise.

	* grub-core/net/net.c (receive_packets): Decrease the stop to 10
	packets but stop only if stop condition is satisfied.
	(grub_net_fs_read_real): Call packets_pulled after real read. Use
	`stall' instead of `eof' as stop condition.
	* grub-core/net/http.c (parse_line): Set `stall' on EOF.
	(http_err): Likewise.
	* grub-core/net/tftp.c (ack): Replace the first argument with data
	instead of socket.
	(tftp_receive): Stall if too many packets are in wait queue.
	(tftp_packets_pulled): New function.
	(grub_tftp_protocol): Set packets_pulled.
	* include/grub/net.h (grub_net_packets): New field count.
	(grub_net_put_packet): Increment count.
	(grub_net_remove_packet): Likewise.
	(grub_net_app_protocol): New field `packets_pulled'.
	(grub_net): New field `stall'.

	* include/grub/net.h (grub_net_poll_cards): New argument stop_condition.
	All users updated.
	* grub-core/net/arp.c (have_pending): New var.
	(pending_req): Likewise.
	(grub_net_arp_send_request): Fill pending_req and use have_pending as
	stop indicator.
	(grub_net_arp_receive): Set have_pending.
	* grub-core/net/dns.c (recv_data): New field stop.
	(recv_hook): Set stop.
	(grub_net_dns_lookup): Init stop and use as stop condition.
	* grub-core/net/http.c (http_establish): Use headers_recv as stop
	condition.
	* grub-core/net/net.c (grub_net_poll_cards): New argument
	stop_condition. Stop when it goes true.
	* grub-core/net/tcp.c (grub_net_tcp_open): Use `established' as stop
	indicator.
	* grub-core/net/tftp.c (tftp_open): Use `have_oack' as stop indicator.

	* grub-core/normal/cmdline.c: Likewise.
	* grub-core/normal/misc.c: Likewise.
	* grub-core/partmap/msdos.c: Likewise.
	* grub-core/parttool/msdospart.c: Likewise.
	* grub-core/script/execute.c: Likewise.
	* grub-core/script/main.c: Likewise.
	* grub-core/term/terminfo.c: Likewise.
	* grub-core/video/bitmap.c: Likewise.
	* util/grub-install.in: Likewise.
	* util/grub-mkimage.c: Likewise.
	* util/grub-mklayout.c: Likewise.
	* util/grub-setup.c: Likewise.

	on it.