libffi_3_3: fix gcc-15 build (#523914)

pkgs/by-name/li/libffi_3_3/package.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchurl,
+  fetchpatch,
 
   doCheck ? true, # test suite depends on dejagnu which cannot be used during bootstrapping
   dejagnu,
@@ -16,7 +17,15 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-cvunkicD3fp6Ao1ROsFahcjVTI1n9V+lpIAohdxlIFY=";
   };
 
-  patches = [ ];
+  patches = [
+    # Backport gcc-15 fix:
+    #   https://github.com/libffi/libffi/pull/861
+    (fetchpatch {
+      name = "gcc-15.patch";
+      url = "https://github.com/libffi/libffi/commit/0859f8431242d5adff21420b9cab538d2af527b5.patch";
+      hash = "sha256-Py4ZAhVyXsfLxr4pnYAH7/lcsQOmpToFgvjQvLg9XVc=";
+    })
+  ];
 
   outputs = [
     "out"