libunwind: use native true executable for build

pkgs/development/libraries/libunwind/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, lib, fetchurl, fetchpatch, autoreconfHook, xz, coreutils }:
+{ stdenv, lib, fetchurl, fetchpatch, autoreconfHook, xz, buildPackages }:
 
 stdenv.mkDerivation rec {
   pname = "libunwind";
@@ -29,7 +29,7 @@ stdenv.mkDerivation rec {
 
   # Without latex2man, no man pages are installed despite being
   # prebuilt in the source tarball.
-  configureFlags = [ "LATEX2MAN=${coreutils}/bin/true" ];
+  configureFlags = [ "LATEX2MAN=${buildPackages.coreutils}/bin/true" ];
 
   propagatedBuildInputs = [ xz ];