Do not require non-empty kernel cmdline
    
    When booting with Fedora-Server-dvd-x86_64-30-20190411.n.0.iso,
    /proc/cmdline is empty (libvirt, qemu host with bios, not sure if that
    matters), after installation to disk, anaconda would "crash" in kernel-core
    %posttrans, after calling kernel-install, because dracut would fail
    with
    > Could not determine the kernel command line parameters.
    > Please specify the kernel command line in /etc/kernel/cmdline!
    
    I guess it's legitimate, even if unusual, to have no cmdline parameters.
    Two changes are done in this patch:
    1. do not fail if the cmdline is empty.
    2. if /usr/lib/kernel/cmdline or /etc/kernel/cmdline are present, but
       empty, ignore /proc/cmdline. If there's explicit configuration to
       have empty cmdline, don't ignore it.
    
    (cherry picked from commit 38b4f4b21c3c6107d7a562fcb432237464440b91)
    
    Resolves: #1746069
    
    patch_name: 0085.patch
    present_in_specfile: true
    location_in_specfile: 85
    squash_commits: true