libcgroup: fix cross compilation

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

···
     hash = "sha256-x2yBqpr3LedtWmpZ4K1ipZxIualNJuDtC4FVGzzcQn8=";
   };
 
-  buildInputs = [ pam bison flex ];
-  nativeBuildInputs = [ autoreconfHook ];
+  nativeBuildInputs = [ autoreconfHook bison flex ];
+  buildInputs = [ pam ];
 
   postPatch = ''
     substituteInPlace src/tools/Makefile.am \