john: Disable building with -march=native.

It prevents john from running with older CPUs such as Core2Duo and gives
an illegal hardware instruction error on these CPUs.

Signed-off-by: aszlig <[e-mail]>

pkgs/tools/security/john/default.nix

···
   NIX_CFLAGS_COMPILE = "-DJOHN_SYSTEMWIDE=1";
 
   preConfigure = "cd src";
+  configureFlags = [ "--disable-native-macro" ];
 
   installPhase = ''
     mkdir -p "$out/share/john"