Re-apply unistd.diff after the update to 0.26.2 am: 20fa8cf97f am: 8cd1c16403 am: 68cee273d4 am: caa9e948f0 am: 3116eb6bc8

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

Change-Id: I3aec52ec188a72da65cd521d7e7ef23c50442d7a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>