The bison elf may call m4 (I saw that building binutils' gold).

svn path=/nixpkgs/branches/stdenv-updates/; revision=18845

pkgs/development/tools/parsing/bison/bison-2.3.nix

···
     url = mirror://gnu/bison/bison-2.3.tar.bz2;
     md5 = "c18640c6ec31a169d351e3117ecce3ec";
   };
+
   buildNativeInputs = [m4];
+  propagatedBuildInputs = [m4];
 
   meta = {
     description = "GNU Bison, a Yacc-compatible parser generator";