Simplify the %post and %postinstall script stuff, it was broken
    
    This approach had multiple problems. The most obvious is a typo -
    it had `%-bindir` instead of `%_bindir`. But you also cannot mix
    a %define into a %post script as was being done here, that just
    doesn't work, you can't track state between scriptlets like that.
    And the `%if` in %posttrans would be resolved at package build
    time, not at %posttrans run time. (I think the syntax was wrong
    anyway). This whole approach was irredeemably broken.
    
    To get things back to a working state quickly, let's just do it
    in a simple-but-dumb way: always run the scripts in %posttrans,
    run them in %post if `ln` is available (with the typo fixed).
    This means we'll often run them twice, but I don't think that
    actually hurts anything. We can refine from here if desired.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>