AU: Exit with status 1 through the Terminator.

This doesn't matter for the target but allows unexpected premature exits through
the Terminator to be caught in unit tests.

BUG=6243
TEST=unit tests, tested interrupting/resuming updates on the device,
tested with a temporary unit test that exited prematurely.

Change-Id: I12b3720d6076487a726e85024a54a2f66594aac5

Review URL: http://codereview.chromium.org/5245002
diff --git a/terminator.cc b/terminator.cc
index 9165afb..abf57c8 100644
--- a/terminator.cc
+++ b/terminator.cc
@@ -18,7 +18,7 @@
 }
 
 void Terminator::Exit() {
-  exit(0);
+  exit(1);
 }
 
 void Terminator::HandleSignal(int signum) {