Use crossystem rather than cros_boot_mode.

SConstruct

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import os
 
 # Protobuffer compilation
 def ProtocolBufferEmitter(target, source, env):
   """ Inputs:
           target: list of targets to compile to
@@ skipping 177 matching lines @@
                              -Wtype-limits
                              -Wtype-limits
                              -Wuninitialized
                              -D__STDC_FORMAT_MACROS=1
                              -D_FILE_OFFSET_BITS=64
                              -I/usr/include/libxml2""".split());
 env['CCFLAGS'] += (' ' + ' '.join(env['CFLAGS']))
 
 env['LIBS'] = Split("""base
                        bz2
-                       cros_boot_mode
                        crypto
                        curl
                        ext2fs
                        gflags
                        glib-2.0
                        gthread-2.0
                        libpcrecpp
                        metrics
                        protobuf
                        pthread
@@ skipping 150 matching lines @@
                                   delta_generator_main)
 
 http_server_cmd = env.Program('test_http_server', 'test_http_server.cc')
 
 unittest_env = env.Clone()
 unittest_env.Append(LIBS=['gmock', 'gtest'])
 unittest_cmd = unittest_env.Program('update_engine_unittests',
                            unittest_sources + unittest_main)
 Clean(unittest_cmd, Glob('*.gcda') + Glob('*.gcno') + Glob('*.gcov') +
                     Split('html app.info'))