ecl: add SBCL as passthru test (#538877)

pkgs/development/compilers/ecl/default.nix

@@ -17,6 +17,7 @@
   threadSupport ? true,
   useBoehmgc ? false,
   boehmgc,
+  sbcl,
 }:
 
 let
@@ -80,6 +81,9 @@ stdenv.mkDerivation rec {
     }"
   '';
 
+  # ECL is used as a bootstrap compiler for SBCL.
+  passthru.tests.sbcl = sbcl;
+
   meta = {
     description = "Lisp implementation aiming to be small, fast and easy to embed";
     homepage = "https://common-lisp.net/project/ecl/";