If the auth status is PENDING, return an NTLM request string. Otherwise

If the auth status is PENDING, return an NTLM request string. Otherwise

	* libsoup/soup-auth.c (ntlm_auth): If the auth status is PENDING,
	return an NTLM request string. Otherwise return the "response"
	field (which should include the NTLM authenticate message)
	(ntlm_init): Don't bother setting "response" to the NTLM request
	string. Just leave it NULL in that case.

	* libsoup/soup-message.c (authorize_handler): Never try to reuse
	an NTLM auth returned from soup_auth_lookup. Only set the auth on
	the connection when it's SOUP_AUTH_STATUS_SUCCESSFUL. Otherwise,
	call soup_auth_set_context() on it just like for non-NTLM auth.
	The net effect of all of this is that now we record when a context
	needs NTLM auth just like with non-NTLM auth, so that that info
	gets preserved across connections.
	(soup_message_requeue): No longer need the hackery here to
	preserve the connection auth state.

	* libsoup/soup-context.c (soup_connection_set_in_use): New, to
	toggle the connection's in_use flag, and set up the death watch
	when it's not in use.
	(connection_death): This is only hooked up when the connection is
	not in use now, so don't need to check that. Should fix the
	infinite connection_death loop.
	(soup_connection_is_new): Keep a distinct "new" flag rather than
	defining "new" as "has been released at least once".
	(soup_connection_set_used): Mark a connection no-longer new.
	(soup_context_connect_cb): Mark the connection as new. Don't set
	up the death watch since it's in_use.
	(try_existing_connections): Use soup_connection_set_in_use.
	(soup_connection_release): Likewise

	* libsoup/soup-message.c (requeue_read_finished): Call
	soup_connection_set_used so that the connection isn't still
	considered new when we send the message the second time.

	* libsoup/soup-queue.c (soup_queue_error_cb): Call
	soup_connection_set_used (assuming we don't close the connection)
	(soup_queue_read_done_cb): Likewise.

	* libsoup/soup-transfer.c (soup_transfer_read_cb): If we read
	nothing, call soup_transfer_read_error_cb rather than just
	cancelling, or else it will get cancelled again later.