Merge "libprocessgroup: UIDs in linux are unsigned" into main am: f8d02eeee1 am: 01d4fdfad3

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

Change-Id: Iea7a39817a8a18497c1dee17b1def58c6706b170
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>