tracing: add lttng support for tracing on linux

This commit adds the ability to enable userspace tracing with lttng
in io.js. It adds tracepoints for all the equivalent dtrace and ETW
tracepoints. To use these tracepoints enable --with-lttng on linux.

PR-URL: https://github.com/iojs/io.js/pull/702


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ryan Graham <ryan@strongloop.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>