Revert "unbound: fix cross-compilation (#370087)"

This reverts commit a8f36e39dc.

A similar change was already pushed to staging (see #364656).

pkgs/by-name/un/unbound/package.nix

@@ -67,7 +67,7 @@ stdenv.mkDerivation (finalAttrs: {
   nativeBuildInputs =
     lib.optionals withMakeWrapper [ makeWrapper ]
     ++ lib.optionals withDNSTAP [ protobufc ]
-    ++ [ pkg-config flex bison ]
+    ++ [ pkg-config flex ]
     ++ lib.optionals withPythonModule [ swig ];
 
   buildInputs = [ openssl nettle expat libevent ]
@@ -121,6 +121,8 @@ stdenv.mkDerivation (finalAttrs: {
     sed -E '/CONFCMDLINE/ s;${storeDir}/[a-z0-9]{32}-;${storeDir}/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-;g' -i config.h
   '';
 
+  nativeCheckInputs = [ bison ];
+
   doCheck = true;
 
   postPatch = lib.optionalString withPythonModule ''