tools: update link to google styleguide for cpplint

This commit updates two old links to Google's C++ styleguide which
currently result in a 404 when accessed.

PR-URL: https://github.com/nodejs/node/pull/30876


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>