cffi-libffi: use ffi.h patch for darwin

This patch was in lisp-modules-new-obsolete, but not applied
here. Without it, cffi-libffi fails to build on darwin.

pkgs/development/lisp-modules/packages.nix

@@ -1,4 +1,4 @@
-{ build-asdf-system, spec, quicklispPackagesFor, pkgs, ... }:
+{ build-asdf-system, spec, quicklispPackagesFor, stdenv, pkgs, ... }:
 
 let
 
@@ -80,6 +80,7 @@ let
       url = "https://github.com/cffi/cffi/archive/3f842b92ef808900bf20dae92c2d74232c2f6d3a.tar.gz";
       sha256 = "1jilvmbbfrmb23j07lwmkbffc6r35wnvas5s4zjc84i856ccclm2";
     };
+    patches = optionals stdenv.isDarwin [ ./patches/cffi-libffi-darwin-ffi-h.patch ];
   };
 
   cl-unicode = build-with-compile-into-pwd {

pkgs/development/lisp-modules/patches/cffi-libffi-darwin-ffi-h.patch

@@ -0,0 +1,14 @@
+--- a/libffi/libffi-types.lisp
++++ b/libffi/libffi-types.lisp
+@@ -43,9 +43,6 @@
+ 
+ (pkg-config-cflags "libffi" :optional t)
+ 
+-#+darwin
+-(include "ffi/ffi.h")
+-#-darwin
+ (include "ffi.h")
+ 
+ (cenum status
+
+Diff finished.  Sun Nov 13 00:23:10 2022