* bench2/bench.rb: Updated to work with new transport
	and new itest.c.
	* bench2/Makefile: Updated for new itest.c
	* bench2/itest.c: Rewritten to use multiple threads
	and automatically divide the workload among the threads.

	* print.c (_stp_print_flush): Move to print_new.c and
	print_old.c.
	* print_new.c: New file containing _stp_print_flush()
	for the new transport.
	* print_old.c: Ditto for old transport.

	* runtime.h (STP_OLD_TRANSPORT): Define
	(errk): Define.
	(MAXSTRINGLEN): Define if not already defined.

	* io.c (_stp_vlog): Use _stp_ctl_write().