android: add licenses

androidndk is apache 2.0
androidsdk is unfree

pkgs/development/mobile/androidenv/androidndk.nix

···
   meta = {
     platforms = stdenv.lib.platforms.linux;
     hydraPlatforms = [];
+    license = stdenv.lib.licenses.asl20;
   };
 }

pkgs/development/mobile/androidenv/androidsdk.nix

···
   meta = {
     platforms = stdenv.lib.platforms.unix;
     hydraPlatforms = [];
+    license = stdenv.lib.licenses.unfree;
   };
 }