AU: Handle firmware update failure when booted from FW slot B.

The firmware updater will fail if we are booted into FW slot B and we
try to update firmware. We shouldn't treat this like a usual update
failure because trying again won't help until we reboot. Thus, with
this CL, we detect this case and request a reboot from the
user. Technically this request is a lie, b/c we are reusing the reboot
request mechanism which tells the user an update has been applied and
thus must be rebooted. We accept this fib since this situation is very
rare: use would have to have 2 FW update updates in a row w/o any
extra boots between.

Also, fix error code in subprocess.

Also, remove execute permissions on a bunch of source files.

BUG=chromium-os:14343
TEST=unittests, tested updates on machine that success, fail, have FW B failure

Review URL: http://codereview.chromium.org/6880077

Change-Id: I2509c6e1c9c9da3ff1ea27da4861c4850bd4d000
diff --git a/update_attempter.h b/update_attempter.h
index d92ff97..02e7162 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -217,6 +217,9 @@
   // Pending error event, if any.
   scoped_ptr<OmahaEvent> error_event_;
 
+  // If we should request a reboot even tho we failed the update
+  bool fake_update_success_;
+
   // HTTP server response code from the last HTTP request action.
   int http_response_code_;