The qemu-dm's log message doesn't have date, time, and pid. It is difficult to find out the message we want.

This patch solves the problem without changing the codes which write messages.

We developed a small program called ioemu-logger. qemu-dm creates a pipe and starts ioemu-logger. qemu-dm associates a stream with the pipe, and sets the stream to existing "logfile" variable. When qemu-dm writes a message to "logfile", ioemu-logger receive it through the pipe and outputs it with date, time and pid to the actual log file.

Signed-off-by: Yuji Shimada <shim...@necst.nec.co.jp>