Merge "Add _Fork() to POSIX header tests." into main am: 6e06348979

Original change: https://android-review.googlesource.com/c/platform/bionic/+/3206173

Change-Id: I4bfb1667082cd40ff47c444be5a0e2c6eec6acc3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>