lispPackages: add serapeum

Adds common-lisp package serapeum (a dependency for Next browser as of
Next v1.4.0), using the quicklisp-to-nix mechanism.

src is overridden and pinned to 65837f8 to deal with
https://github.com/ruricolist/serapeum/issues/42

pkgs/development/lisp-modules/quicklisp-to-nix-overrides.nix

@@ -105,6 +105,18 @@ $out/lib/common-lisp/query-fs"
       '';
     };
   };
+  serapeum = x: {
+    overrides = y: (x.overrides y) //{
+      # Override src until quicklisp catches up to 65837f8 (see serapeum
+      # issue #42)
+      src = pkgs.fetchFromGitHub {
+        owner = "ruricolist";
+        repo = "serapeum";
+        rev = "65837f8a0d65b36369ec8d000fff5c29a395b5fe";
+        sha256 = "0clwf81r2lvk1rbfvk91s9zmbkas9imf57ilqclw12mxaxlfsnbw";
+      };
+    };
+  };
   sqlite = x: {
     propagatedBuildInputs = [pkgs.sqlite];
     overrides = y: (x.overrides y) // {