Merge "Add support for only starting 64 bit zygote." am: 1012626192

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2061509

Change-Id: I16d2104ef124cd3bee86923f36c80352117ff69f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>