kodi: inherit underlying kodi's meta when wrapping

kodi has a mainProgram:

```
nix-repl> kodi.meta.mainProgram
"kodi"
```

But when wrapping it, we'd lose its mainProgram:

```
nix-repl> (kodi.withPackages (_: [])).meta.mainProgram
error:
       … while evaluating the attribute 'meta.mainProgram'
       ...

       error: attribute 'mainProgram' missing
       at «string»:1:1:
            1| (kodi.withPackages (_: [])).meta.mainProgram
             | ^
```

This fixes that. Please let me know if there's a better pattern
to follow for inheriting meta information when wrapping. I intentionally
didn't inherit the full `meta` attribute as it has some other
information (such as `position`) that I think are better *not*
inherited.

pkgs/applications/video/kodi/wrapper.nix

@@ -50,4 +50,8 @@ buildEnv {
         }"
     done
   '';
+
+  meta = {
+    inherit (kodi.meta) mainProgram;
+  };
 }