anchor.diff:  , libx11
   , libxrandr
   , libxrender
  -, mesa
  +, opengl-dummy
   , renderproto
   , systemd_lib
   , wayland
  
positive.code:     "--enable-encoders"
      "--${boolEn (libdrm != null)}-drm"
      "--${boolEn (libx11 != null)}-x11"
      "--${boolEn (libx11 != null && mesa != null)}-glx"
      "--${boolEn (wayland != null)}-wayland"
      "--${boolEn (wayland != null && mesa != null)}-egl"
      "--disable-gtk-doc"
      "--disable-gtk-doc-html"
      "--disable-gtk-doc-pdf"
  
negative.code:     libx11
      libxrandr
      libxrender
      opengl-dummy
      renderproto
      systemd_lib
      wayland
  