Move hardware and boot_control implementation to libupdate_engine.

The implementations of the BootControlInterface and HardwareInterface
are specific to the platform and use case. The delta_generator uses the
DeltaPerformer in the libpayload_consumer to apply a payload to a set
of partitions defined as local files, for example.

This patch move the platform implementations, not available when
building for the host back to the libupdate_engine.

Bug: 24619596
TEST=mma

Change-Id: I16ab06c2e53dfd046e693bdb7310ec26a2d69054
diff --git a/update_engine.gyp b/update_engine.gyp
index c21edc2..2fa6ae8 100644
--- a/update_engine.gyp
+++ b/update_engine.gyp
@@ -146,19 +146,15 @@
         },
         'libraries': [
           '-lbz2',
-          '-lrootdev',
           '-lrt',
-          '-lvboot_host',
         ],
       },
       'sources': [
         'common/action_processor.cc',
-        'common/boot_control_chromeos.cc',
         'common/boot_control_stub.cc',
         'common/certificate_checker.cc',
         'common/clock.cc',
         'common/constants.cc',
-        'common/hardware_chromeos.cc',
         'common/hash_calculator.cc',
         'common/http_common.cc',
         'common/http_fetcher.cc',
@@ -242,10 +238,12 @@
         ],
       },
       'sources': [
+        'boot_control_chromeos.cc',
         'chrome_browser_proxy_resolver.cc',
         'connection_manager.cc',
         'daemon.cc',
         'dbus_service.cc',
+        'hardware_chromeos.cc',
         'image_properties_chromeos.cc',
         'libcros_proxy.cc',
         'metrics.cc',