/usr/share/emacs25/site-lisp/subdirs.el is in emacs25-common 25.2+1-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | (if (fboundp 'normal-top-level-add-subdirs-to-load-path)
(normal-top-level-add-subdirs-to-load-path))
|