storageproxy: Report fsync failures with a distinct error code am: cf458bae

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/19517837



Change-Id: I0cec6b12306b037503160b56ceecdb95acc4bde3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>