[GN] Fix tools/gn/bootstrap/bootstrap.py.

Update the list of files required to boostrap gn (best-effort).
Tested that gn is build successfully on macOS.

BUG=None

Review-Url: https://codereview.chromium.org/2538903003
Cr-Original-Commit-Position: refs/heads/master@{#435273}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: eace899f8a53284c3618940122caa858c03c602c
1 file changed
tree: 7f6fe164de9fbfdcd2f070fe5fdc7e3539936e4f
  1. tools/