src: add missing "http_parser.h" include

In 9d522225 the indirect "http_parser.h"
include was removed, which made `NODE_STRINGIFY()` fail silently for the
http parser version in `process.versions`.

PR-URL: https://github.com/nodejs/node/pull/12464
Fixes: https://github.com/nodejs/node/issues/12463
Ref: https://github.com/nodejs/node/pull/12366


Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Alexey Orlenko <eaglexrlnk@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>