Fail gracefully when we fail to fork the update binary

This change was original made in cw-f-dev but caused failures in
nyc-mr1-dev-plus-aosp due to lack of support for 'LOGE'

This version of the change uses the new 'LOG(ERROR)' style logging
instead.

See bug b/31395655
Test: attempt a memory intensive incremental OTA on a low-memory device

Change-Id: Ia87d989a66b0ce3f48e862abf9b9d6943f70e554
(cherry picked from commit c8db4817)