CPack/Deb: Restore setting of root as the owner of files
Fixes a regression introduced in !1181 (merged) (commit df556e65, switching from OpenBSD's 'ar' to libarchive) that affects v3.10.0-rc1 to current.
Not all the files were having their UID/GID blanked to 0/root. When using libarchive and if the UID of the current user is large, CPack generation of .deb files would fail with
#error:archive_write_header: Numeric user ID too large
With this fix .deb generation works again.
Topic-rename: cpack-fix-deb-packaging