chore: checkpoint before Python removal

vendor/zerocopy/benches/split_at_dynamic_padding.rs

@@ -0,0 +1,12 @@
+use zerocopy::*;
+
+#[path = "formats/coco_dynamic_padding.rs"]
+mod format;
+
+#[unsafe(no_mangle)]
+fn bench_split_at_dynamic_padding(
+    source: &format::CocoPacket,
+    len: usize,
+) -> Option<Split<&format::CocoPacket>> {
+    source.split_at(len)
+}