More clean-ups
    
    - Classify buildreqs by usage
    - Package Changes file
    - Simplify find command using -delete
    - Don't need to remove empty directories from the buildroot
    - Drop redundant perl default filter
    - Use DESTDIR rather than PERL_INSTALL_ROOT
    - Use %{_fixperms} macro rather than our own chmod incantation
    - Don't need to specify OPTIMIZE for noarch package
    - Fix bogus dates in changelog