rpm/kernel-source.spec.in: temporary workaround for a build failure
    
    Upstream c6x architecture removal left a dangling link behind which
    triggers openSUSE post-build check in kernel-source, failing
    kernel-source build.
    
    A fix deleting the danglink link has been submitted but it did not make
    it into 5.12-rc1. Unfortunately we cannot add it as a patch as patch
    utility does not handle symlink removal. Add a temporary band-aid which
    deletes all dangling symlinks after unpacking the kernel source tarball.
    
    [jslaby] It's not that temporary as we are dragging this for quite some
    time in master. The reason is that this can happen any time again, so
    let's have this in packaging instead.