Merge "libprocessgroup: UIDs in linux are unsigned" into main am: f8d02eeee1

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2677642

Change-Id: I9bcc66576d12fa017d424ff9a4b505980d9d5f68
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>