Merge "libprocessgroup: Handle temporarily non-empty group removal failure" am: 6cd136fc61

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2108506

Change-Id: I5fd23f113a484f4eb0d2b2b33038934b880a4dd0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>