libmikmod: split out/dev/man outputs

This prevents propagating many dev dependencies into non-dev dependents.

pkgs/development/libraries/libmikmod/default.nix

@@ -18,8 +18,14 @@ in stdenv.mkDerivation rec {
   propagatedBuildInputs =
     optional stdenv.isLinux libpulseaudio;
 
+  outputs = [ "out" "dev" "man" ];
+
   NIX_LDFLAGS = optionalString stdenv.isLinux "-lasound";
 
+  postInstall = ''
+    moveToOutput bin/libmikmod-config "$dev"
+  '';
+
   meta = with lib; {
     description = "A library for playing tracker music module files";
     homepage    = "https://mikmod.shlomifish.org/";