ax25-apps: set localstatedir to /var/lib

Previously, localstatedir was being defaulting to path inside /nix/store
so some AX.25 applications were not able to write their state to disk.

pkgs/applications/radio/ax25-apps/default.nix

@@ -20,6 +20,7 @@ stdenv.mkDerivation rec {
 
   configureFlags = [
     "--sysconfdir=/etc"
+    "--localstatedir=/var/lib"
     "--program-transform-name=s@^call$@ax&@;s@^listen$@ax&@"
   ];