Allow the vendor partition to be in /system/vendor. am: 7eacdf8e53

Original change: https://android-review.googlesource.com/c/platform/art/+/2216741

Change-Id: I586960784be9fba8c47af4f9822a4005e6a07c83
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>