ecl: fix build with libffi 3.3

The build was broken by the recent libffi update
(53a04a2df0) because of this upstream
change:

https://github.com/libffi/libffi/commit/ef76205647bca77796882d31f6ab5e889f461f07

I have changed the usage of FFI_SYSV as gentoo suggests:

https://wiki.gentoo.org/wiki/Libffi_3.3_porting_notes/FFI_SYSV

I'm not entirely sure if that is the right call here, but I haven't
noticed any regressions in my testing and its definitely better than a
broken build.

Upstream: https://gitlab.com/embeddable-common-lisp/ecl/issues/302

pkgs/development/compilers/ecl/16.1.2.nix

@@ -61,6 +61,7 @@ stdenv.mkDerivation {
       url = "https://git.sagemath.org/sage.git/plain/build/pkgs/ecl/patches/16.1.2-getcwd.patch?id=07d6c37d18811e2b377a9689790a7c5e24da16ba";
       sha256 = "1fbi8gn7rv8nqff5mpaijsrch3k3z7qc5cn4h1vl8qrr8xwqlqhb";
     })
+    ./ecl-1.16.2-libffi-3.3-abi.patch
   ];
 
   hardeningDisable = [ "format" ];