benchmark: fix child-process-read on Windows

Under Windows 'ipc' communication requires the other process to format
its messages with 'IPC framing protocol'. Otherwise, an assert is
triggered in libuv. This commit changes child-process-read benchmark
to use stdout to communicate with parent process. It also adds
child-process-read-ipc.js to benchmark IPC communication using
child node process.

PR-URL: https://github.com/nodejs/node/pull/6971


Reviewed-By: João Reis <reis@janeasystems.com>
Reviewed-By: James M Snell <jasnell@gmail.com>