Merge "Don't write out cargo.out if it wasn't generated." into main am: 21592eede9

Original change: https://android-review.googlesource.com/c/platform/development/+/3073727

Change-Id: I10633d5342b1a89cbeb58af5f15a49906f522167
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>