Aconfigd: send an error message back thru socket in case of error am: cdf0f5c61f

Original change: https://android-review.googlesource.com/c/platform/system/server_configurable_flags/+/3371875

Change-Id: I9d2b095681d89d487b2991ed5e5b39cb3f90ef2e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>