[automerger skipped] cleanup - remove tun.h am: 551367e946 am: 6c944012c2 -s ours

am skip reason: Change-Id I7c3a986584aa3d02519545fb928457b61247ed14 with SHA-1 551367e946 is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/android-clat/+/11736439

Change-Id: Ia1e01b3a96f9bd03ebbd4f37a539201e80da0837