$docdev fixups: mostly to avoid empty output

... after auto-removing some kinds of files by default.
In some cases I let them be removed and in others I let them be put into
$docdev. That was more due to general indecisiveness on this question
than any reasons in the particular cases.

pkgs/development/libraries/SDL/default.nix

@@ -26,7 +26,7 @@ stdenv.mkDerivation rec {
     sha256 = "005d993xcac8236fpvd1iawkz4wqjybkpn8dbwaliqz5jfkidlyn";
   };
 
-  outputs = [ "dev" "out" "man" ];
+  outputs = [ "dev" "out" ];
   outputBin = "dev"; # sdl-config
 
   nativeBuildInputs = [ pkgconfig ];