Disable openssl test on too old nixpkgs

There on nixpkgs 22 and lower, there is too old Rust to build OpenSSL

test/fast/openssl/default.nix

@@ -1,8 +1,33 @@
 # OpenSSL needs `pkg-config` and `openssl` buildInputs. This tests whether we correctly supply them automatically.
 
-{ naersk, ... }:
+{ naersk, pkgs, ... }:
 
-naersk.buildPackage {
-  src = ./fixtures;
-  doCheck = true;
-}
+let
+  # Whether the nixpkgs is version 23 or newer, because in older nixpkgs, rustc is too old to build openssl.
+  buildIt = with pkgs.lib;
+    (strings.toInt ((builtins.elemAt (splitString "." trivial.version) 0)) >= 23);
+in
+
+if buildIt then
+  naersk.buildPackage {
+    src = ./fixtures;
+    doCheck = true;
+  }
+else
+  builtins.trace ''
+      Not building OpenSSL test, because Rust from nixpkgs under major version 23 cannot build OpenSSL
+      Current nixpkgs version: ${pkgs.lib.trivial.version}
+    ''
+
+    pkgs.stdenv.mkDerivation {
+      name = "not-building-openssl-test";
+
+      dontUnpack = true;
+
+      buildPhase = ''
+        echo Not building OpenSSL test, because Rust from nixpkgs under major version 23 cannot build OpenSSL
+        echo Current nixpkgs version: ${pkgs.lib.trivial.version}
+      '';
+
+      installPhase = "mkdir $out";
+    }