Prepare for bin-sbin merge
    
    https://fedoraproject.org/wiki/Changes/Unify_bin_and_sbin
    
    First, fix build if %_sbindir == %_bindir.
    
    Second, add Provides for the old locations. We rely on the
    filesystem(unmerged-sbin-symlinks) feature to actually create the symlinks
    for us.
    
    This commit makes things compatible with the state before and after the merge.