move %systemd_post{,un} to the correct subpackage
    
    ... to avoid the following scriptlet failures:
    
      Upgrading   : libnghttp2-1.20.0-1.fc24.x86_64
    /sbin/ldconfig: relative path `2' used to build cache
    warning: %post(libnghttp2-1.20.0-1.fc24.x86_64) scriptlet failed, exit status 1
    Non-fatal POSTIN scriptlet failure in rpm package libnghttp2
    Non-fatal POSTIN scriptlet failure in rpm package libnghttp2
      Upgrading   : nghttp2-1.20.0-1.fc24.x86_64