Merge "first_stage_mount: Bind mount /system after switch root" am: 53f1fab6 am: c3e43e63

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2146960



Change-Id: I98d3abaaf8871251817f83ae198e3b9fc7214401
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>