build: add missing src/tracing header files

I noticed that only one header from src/tracing is included in the
sources list in node.gyp. Not sure if this is intentional or not so I
wanted to bring it up just in case this was overlooked.

PR-URL: https://github.com/nodejs/node/pull/10851


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>