Add more comments about the return codes of profman. am: 99fc5bb7a7 am: 4eb3f0a6ff am: 69ab0e7141

Original change: https://android-review.googlesource.com/c/platform/art/+/2203780

Change-Id: I2e9142bb35cb444b753dbffe893b571c567484f1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>