anchor.diff:      "--disable-gtk-doc-pdf"
       "--enable-nls"
       "--enable-rpath"
  -    "--enable-introspection"
  +    (enFlag "introspection" (gobject-introspection != null) null)
       "--with-x"
     ];
   
  
positive.code:     "--disable-standalone"
      "--disable-debug"
      (enFlag "unit-tests" doCheck null)
      "--enable-cairo"
      "--disable-profile"
      "--disable-maintainer-flags"
      "--enable-deprecated"
      "--enable-glibtest"
      "--enable-glib"
      "--enable-cogl-pango"
      "--enable-cogl-gst"
      "--enable-cogl-path"
      "--enable-gdk-pixbuf"
      "--disable-quartz-image"
      "--disable-examples-install"
      "--enable-gles1"
  
negative.code:     gdk-pixbuf
      glib
      gobject-introspection
      gst-plugins-base
      gstreamer
      json-glib
      libdrm
      libxkbcommon
  