nixos-firewall-tool: fix cross-compilation (#370712)

pkgs/by-name/ni/nixos-firewall-tool/package.nix

@@ -14,6 +14,7 @@ stdenvNoCC.mkDerivation {
   strictDeps = true;
   buildInputs = [ bash ];
   nativeBuildInputs = [ installShellFiles ];
+  nativeCheckInputs = [ shellcheck-minimal ];
 
   postPatch = ''
     patchShebangs --host nixos-firewall-tool
@@ -30,7 +31,7 @@ stdenvNoCC.mkDerivation {
     lib.meta.availableOn stdenvNoCC.buildPlatform shellcheck-minimal.compiler
     && (builtins.tryEval shellcheck-minimal.compiler.outPath).success;
   checkPhase = ''
-    ${lib.getExe shellcheck-minimal} nixos-firewall-tool
+    shellcheck nixos-firewall-tool
   '';
 
   meta = with lib; {