Improve adherence with current Fedora packaging guidelines
    
    - Add support for DESTDIR.
    - Remove extra license patch in order to use %license.
    - Make usage of scriptlets %make_build, %make_install and
      %ldconfig_scriptlets.
    - Prevent unintentional soname bumps by specifying it via %soname.
    - Use %global instead of %define for %{cpu_variants}.
    - Remove unintentional usage of %{_isa}.