c2ffi: Fix passthru.updateScript settings

pkgs/development/tools/misc/c2ffi/default.nix

···
   passthru.updateScript = unstableGitUpdater {
     url = "https://github.com/rpav/c2ffi.git";
     branch = c2ffiBranch;
+    # Tags only exist for older LLVM versions, so they would result in nonsense names
+    # like: c2ffi-llvm-16.0.0-11.0.0.0-unstable-YYYY-MM-DD
+    hardcodeZeroVersion = true;
   };
 
   nativeBuildInputs = [