Bug 578578 - fix AUTO_BUILD was elevated to INCREMENTAL_BUILD

after the first iteration and could not be interrupted by user actions
anymore.

Change-Id: Ibe3900ab7b0f50ad912060bb905d5ef98c7b9c56
Signed-off-by: Joerg Kubitz <jkubitz-eclipse@gmx.de>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.resources/+/190559
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Sebastian Zarnekow <sebastian.zarnekow@gmail.com>