Patch adapted from Sage. Allows building ECL on libffi 3.3.
diff --git a/src/c/ffi.d b/src/c/ffi.d
index 8861303e..8a959c23 100644
--- a/src/c/ffi.d
+++ b/src/c/ffi.d
@@ -133,8 +133,8 @@ static struct {
 #elif defined(X86_WIN64)
   {@':win64', FFI_WIN64},
 #elif defined(X86_ANY) || defined(X86) || defined(X86_64)
-  {@':cdecl', FFI_SYSV},
-  {@':sysv', FFI_SYSV},
+  {@':cdecl', FFI_UNIX64},
+  {@':sysv', FFI_UNIX64},
   {@':unix64', FFI_UNIX64},
 #endif
 };
/cgit-static/cgit.png' alt='cgit logo'/></a></td>
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<tr><td><span title='2020-12-23 17:30:14 +0100'>2020-12-23</span></td><td><a href='/guix/commit/etc/snippets/scheme-mode?id=d6b0d219c6e4e8392fbeb3263c95e9b7d7c75e1c'>etc: snippets: Add new build systems to package snippet.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/snippets/scheme-mode/guix-package: Add the following as possibilities
for the build-system field:

clojure-build-system
copy-build-system
dune-build-system
guile-build-system
julia-build-system
linux-module-build-system
maven-build-system
node-build-system
qt-build-system
rakudo-build-system

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Morgan Smith</td></tr>