gsasl: Add and test

pkgs/development/libraries/gsasl/default.nix

···
-{ fetchurl, lib, stdenv, libidn, libkrb5 }:
+{ fetchurl, lib, stdenv, libidn, libkrb5
+, testers
+}:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   pname = "gsasl";
   version = "2.2.0";
 
   src = fetchurl {
-    url = "mirror://gnu/gsasl/${pname}-${version}.tar.gz";
+    url = "mirror://gnu/gsasl/${finalAttrs.pname}-${finalAttrs.version}.tar.gz";
     sha256 = "sha256-ebho47mXbcSE1ZspygroiXvpbOTTbTKu1dk1p6Mwd1k=";
   };
 
···
     export LOCALDOMAIN="dummydomain"
   '';
   doCheck = !stdenv.hostPlatform.isDarwin;
+
+  passthru.tests.pkg-config = testers.testMetaPkgConfig finalAttrs.finalPackage;
 
   meta = {
     description = "GNU SASL, Simple Authentication and Security Layer library";
···
     license = lib.licenses.gpl3Plus;
 
     maintainers = with lib.maintainers; [ shlevy ];
+    pkgConfigModules = [ "libgsasl" ];
     platforms = lib.platforms.all;
   };
-}
+})