[m-rev.] for post-commit review: avoid duplicating file_names.m's code

[Zoltan Somogyi]

For review by anyone.

Zoltan.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Log.fnd
Type: application/octet-stream
Size: 1600 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20230819/e120addb/attachment-0002.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DIFF.fnd
Type: application/octet-stream
Size: 19142 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20230819/e120addb/attachment-0003.obj>