packages set to install on first login w/ OS install copies instead of symlinks

[Rob LaRose]

When a workflow includes an OS install, packages set to “on first user login” are being copied to the workflow directory instead of symlinked. This seems wrong.

On non-OS (package-only) installs, packages are symlinked as expected from the Shared Packages directory.

[timothy perfitt]

optimization but needed. slating for 2.3.