build: add `library_files` to gyp variables

GYP uses the system path when parsing node.gyp;
However, if system python is different from our
gyp runtime python, like '2.7', gyp would crash.

Co-authored-by: Michaël Zasso <targos@protonmail.com>

PR-URL: https://github.com/nodejs/node/pull/39293


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>