Don't fork the daemon.

Init requires daemons to run without forking.

Bug: 23186405
Change-Id: Ie8a23159e0b6f80d9a6d68da085ba52b10422598
diff --git a/update_engine.rc b/update_engine.rc
index 785d7af..1b48da4 100644
--- a/update_engine.rc
+++ b/update_engine.rc
@@ -1,7 +1,7 @@
 on boot
     mkdir /data/misc/update_engine 0700 system system
 
-service update_engine /system/bin/update_engine --logtostderr
+service update_engine /system/bin/update_engine --logtostderr --foreground
     class main
     user system
     group system dbus inet