Use a "rich dependency" for the system-release req
    
    Before this change, lvm2 pulls in fedora-release (or equivalent) which
    pulls in a bunch of other packages, e.g. fedora-repos. This is
    unnecessary for example in minimal constainers or initrd images. By
    specifying the dependency conditionally, it will be satisfied on all
    normal systems, while making it easier to skip in custom setups.
    (filesystem requires setup which requires system-release, so normally
    systemd-release always must be installed.) Also, use Requires(post)
    because it is only used for presets which are used in %post. This
    allows the system-release package to be removed after the installation
    from the system.