fix jfsutils cross compilation

pkgs/tools/filesystems/jfsutils/ar-fix.patch

···
+--- jfsutils-1.1.15/configure.in.orig	2018-11-27 20:46:55.830242385 +0300
++++ jfsutils-1.1.15/configure.in	2018-11-27 20:47:00.596307630 +0300
+@@ -15,6 +15,7 @@
+ AC_PATH_PROG(LN, ln, ln)
+ AC_PROG_LN_S
+ AC_PROG_RANLIB
++AM_PROG_AR
+ 
+ dnl Checks for header files.
+ AC_HEADER_STDC

pkgs/tools/filesystems/jfsutils/default.nix

···
-{ stdenv, fetchurl, libuuid }:
+{ stdenv, fetchurl, libuuid, autoreconfHook }:
 
 stdenv.mkDerivation rec {
   name = "jfsutils-1.1.15";
···
     sha256 = "0kbsy2sk1jv4m82rxyl25gwrlkzvl3hzdga9gshkxkhm83v1aji4";
   };
 
-  patches = [ ./types.patch ./hardening-format.patch ];
+  patches = [
+    ./types.patch
+    ./hardening-format.patch
+    # required for cross-compilation
+    ./ar-fix.patch
+  ];
 
+  nativeBuildInputs = [ autoreconfHook ];
   buildInputs = [ libuuid ];
 
   meta = with stdenv.lib; {