Parse and expose end-of-life flag.

Omaha update or noupdate response can include _key=value pairs with
arbitrary data. One of those key can be "_eol" with the one of the
values "supported", "security-only" or "eol" which notifies the device
the end-of-life status of the device with respect to updates. This
information is now exposed via GetEolStatus() to the client so it
can be properly displayed in the UI.

Bug: 27924505
TEST=Added unittest. Run `update_engine_client --eol_status` on link.

Change-Id: Icc15f25b4d0b19cc894f5afc52ac7c43c7818982
diff --git a/Android.mk b/Android.mk
index 107a844..93c6c87 100644
--- a/Android.mk
+++ b/Android.mk
@@ -315,6 +315,7 @@
     omaha_request_action.cc \
     omaha_request_params.cc \
     omaha_response_handler_action.cc \
+    omaha_utils.cc \
     p2p_manager.cc \
     payload_state.cc \
     proxy_resolver.cc \
@@ -524,7 +525,8 @@
     libupdate_engine_client
 LOCAL_SRC_FILES := \
     update_engine_client.cc \
-    common/error_code_utils.cc
+    common/error_code_utils.cc \
+    omaha_utils.cc
 else  # !defined(BRILLO)
 #TODO(deymo): Remove external/cros/system_api/dbus once the strings are moved
 # out of the DBus interface.
@@ -904,6 +906,7 @@
     omaha_request_action_unittest.cc \
     omaha_request_params_unittest.cc \
     omaha_response_handler_action_unittest.cc \
+    omaha_utils_unittest.cc \
     p2p_manager_unittest.cc \
     payload_consumer/bzip_extent_writer_unittest.cc \
     payload_consumer/delta_performer_integration_test.cc \