* admin/archive-contents.el (archive--process-simple-package):
Copy file if it is a symlink to prevent deletion of target source
file.
(archive--core-package-link-file): Rename from
archive--core-package-copy-file. Create symbolic links for core
files.
(archive--core-package-link-directory): Rename from
archive--core-package-copy-directory. Call
archive--core-package-link-file.
(archive--core-package-sync): Change message to indicate linking.
Call archive--core-package-link-file.