anchor.diff:      glib
       libpng
       libspectre
  +    lzo
  +    opengl-dummy
  +    xorg.pixman
  +    zlib
  +  ]  ++ optionals opengl-dummy.glx [
       libx11
       libxcb
  -    lzo
  -    opengl-dummy
       xorg.libXext
       xorg.libXrender
  -    xorg.pixman
  -    zlib
     ];
   
     patches = [
  
positive.code:     "--disable-gallium"
      # Only one OpenGL backend may be selected at compile time
      # OpenGL X (gl), or OpenGL ES 2.0 (glesv2)
      "--${boolEn (!opengl-dummy.glexv2 && opengl-dummy.glx)}-gl"
      "--${boolEn opengl-dummy.glesv2}-glesv2"
      "--disable-cogl"  # recursive dependency
      # FIXME: fix directfb mirroring
  
negative.code:        Freetype `-I' cflags from being propagated. */ ''
        sed -i src/cairo.pc.in \
          -e 's|^Cflags:\(.*\)$|Cflags: \1 -I${freetype}/include/freetype2 -I${freetype}/include|g'
      '' + optionalString (!opengl-dummy.glx)
      /* tests and perf tools require Xorg */ ''
        sed -i Makefile.am \
          -e '/^SUBDIRS/ s#boilerplate test perf# #'
  