htop: touch all headers

Fix the following build failure:

```
config.status: executing libtool commands
building
make flags: SHELL=/nix/store/548wfw1i43glkx8lkyjmbg59h6127qky-bash-4.3-p39/bin/bash
./scripts/MakeHeader.py ColumnsPanel.c
/usr/bin/env: python: No such file or directory
Makefile:2164: recipe for target 'ColumnsPanel.h' failed
make: *** [ColumnsPanel.h] Error 127
builder for ‘/nix/store/6rai1vs6jsw8y5z5jff98f0f8jzfa12n-htop-1.0.3-584-8f07868f.drv’ failed with exit code 2
```

pkgs/os-specific/linux/htop/default.nix

@@ -13,6 +13,10 @@ stdenv.mkDerivation rec {
   buildInputs = [ ncurses ];
   nativeBuildInputs = [ autoreconfHook ];
 
+  postPatch = ''
+    touch *.h # unnecessary regeneration requires Python
+  '';
+
   meta = {
     description = "An interactive process viewer for Linux";
     homepage = "http://htop.sourceforge.net";