turn remote into a to_xclose target

this turns the remote into a to_xclose target
it now subclasses target_ops and puts the remote state there

this isn't really complete unfortunately
I think remote_protocol_packets must be made per-remote
also perhaps the "notif" stuff -- I forget

2014-07-29  Tom Tromey  <tromey@redhat.com>

	* remote.c (remote_ops, extended_remote_ops): Move earlier.
	(struct remote_ops_with_data): New.
	(remote_state): Remove.
	(REMOTE_TARGET_STRATUM): New define.
	(get_remote_state_raw): Redefine.
	(new_remote_state): Return void and take a remote_state as a
	parameter.  Update.
	(destroy_remote_state): New function.
	(get_remote_state): Return NULL if get_remote_state_raw does.
	(init_remote_state, get_remote_packet_size, remote_threads_info)
	(remote_threads_extra_info): Check for rs==NULL.
	(remote_xclose): Rename from remote_close.  Call
	destroy_remote_state.  Free "self".
	(remote_unpush_target): Use REMOTE_TARGET_STRATUM.
	(remote_open_1): Check for rs==NULL.  Use TARGET_NEW.
	(discard_pending_stop_replies): Check for rs==NULL.
	(remote_mourn_1): Update comment.
	(packet_command, remote_file_put, remote_file_get)
	(remote_file_delete): Check for rs==NULL.
	(init_remote_ops): Set to_xclose, not to_close.  Use
	REMOTE_TARGET_STRATUM.
	(remote_new_objfile, set_range_stepping): Check for rs==NULL.
	(_initialize_remote): Don't call new_remote_state.