Re-apply unistd.diff after the update to 0.26.2 am: 20fa8cf97f

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/nix/+/2445822

Change-Id: Ib22acb8ba1b432cce3f6446cbad8d23bd38472a0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>