Turn some license strings into lib.licenses values

pkgs/development/python-modules/dbus/default.nix

@@ -17,6 +17,6 @@ stdenv.mkDerivation rec {
 
   meta = {
     description = "Python DBus bindings";
-    license = "MIT";
+    license = stdenv.lib.licenses.mit;
   };
 }

pkgs/development/python-modules/pygame/default.nix

@@ -32,6 +32,6 @@ stdenv.mkDerivation {
   meta = {
     description = "Python library for games";
     homepage = "http://www.pygame.org/";
-    license = "LGPLv2.1+";
+    license = stdenv.lib.licenses.lgpl21Plus;
   };
 }

pkgs/development/python-modules/pyx/default.nix

@@ -34,7 +34,7 @@ stdenv.mkDerivation rec {
       plots in publication-ready quality are built out of these
       primitives.
     '';
-    license = "GPLv2";
+    license = stdenv.lib.licenses.gpl2;
     homepage = http://pyx.sourceforge.net/;
   };
 }