init: log when 'user' is unspecified

NOTE: in master, but should be submitted in AOSP.
Waiting to hear from security folks. Also might
need cleanup.

Not currently done. Seems errorprone.

Bug: 276813155
Test: boot, check logs
Change-Id: I7cbc39b282889dd582f06a8eedc38ae637c8edec
5 files changed