Add a feature to get the last UpdateAttempt ErrorCode from update_engine

For autotest, update_engine test failures are always hard to debug,
since the error message is not clear. Add a new flag 'last_attempt_error'
to get the last UpdateAttempt ErrorCode from update_engine.

Bug:25598547
Test:emerge-peppy update_engine
     emerge-peppy update_engine_client
     cros flash a test image to DUT.
     (on the DUT):update_engine_client --last_attempt_error
     Compare the results with the update_engine logs, matched.

Change-Id: Id12681097ed30b0826cad68809f17f934a07e5b2
diff --git a/Android.mk b/Android.mk
index 0b30720..07d8f64 100644
--- a/Android.mk
+++ b/Android.mk
@@ -465,7 +465,8 @@
 LOCAL_SHARED_LIBRARIES += \
     libupdate_engine_client
 LOCAL_SRC_FILES := \
-    update_engine_client.cc
+    update_engine_client.cc \
+    common/error_code_utils.cc
 else  # !defined(BRILLO)
 #TODO(deymo): Remove external/cros/system_api/dbus once the strings are moved
 # out of the DBus interface.