Merge "libprocessgroup: Add argument checks in KillProcessGroup()" am:...

Merge "libprocessgroup: Add argument checks in KillProcessGroup()" am: 1d25c20a am: cca74678 am: a1a60eed

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2475609



Change-Id: Id336b422b81c4869413f7e82965689d604eeab2d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>