qt: fix broken download url for qt4

qt4 has been moved to archive and now needs to be fetched from there.
md5 has not changed - it is the same package.

component/qt/buildout.cfg

@@ -43,7 +43,7 @@ post-install =
 # qmake binary can be reached directly from ${qt:location}/bin/qmake if [qt] is fully built
 recipe = slapos.recipe.cmmi
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
-url = http://download.qt.io/official_releases/qt/4.8/4.8.7/qt-everywhere-opensource-src-4.8.7.tar.gz
+url = http://download.qt.io/archive/qt/4.8/4.8.7/qt-everywhere-opensource-src-4.8.7.tar.gz
 md5sum = d990ee66bf7ab0c785589776f35ba6ad
 # see https://github.com/NixOS/nixpkgs/blob/3e387c3e005c87566b5403d24c86f71f4945a79b/pkgs/development/libraries/qt-4.x/4.8/default.nix#L101
 pre-configure =