Merge "aflags: make flag storage error message more user-friendly" into main am: 1986c86bb2

Original change: https://android-review.googlesource.com/c/platform/build/+/2995977

Change-Id: If50b72c08b6feef7ced1383794f9a791c6963ae8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>