Drop supplementary groups for child zygotes. am: 7c8779c0 am: 80cfa981 am:...

Drop supplementary groups for child zygotes. am: 7c8779c0 am: 80cfa981 am: 75f35b04 am: 69db3557 am: a0f8e3b7 am: 4fbfaca6

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11691614

Change-Id: I39377e36a7bacd1c0f7565bfdcd030028762b682