Cleanup: Use Bit('build_ARCH') instead of Bit('target_ARCH')

tools/scons_to_gn/test.scons

 # Copyright (c) 2014 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file
 
 # Test file for scons_to_gn
 
 sources = ['A.c', 'B.c', 'C.c']
 defines = []
 
 if env.Bit('win'):
   sources += ['win']
-if env.Bit('target_x86_32'):
+if env.Bit('build_x86_32'):
   defines += ['_x86']
-if env.Bit('target_x86_64'):
+if env.Bit('build_x86_64'):
   defines += ['_x64']
 
 if True:
   sources += ['FOOBAR.c']
 
 env.ComponentLibrary('all', sources, CFLAGS=['-D' + x for x in defines])
 
 nacl_env = env.Clone()
 nacl_env.Append(CFLAGS=['-DNACL'])
 
 if nacl_env.Bit('win'):
   nacl_env.ComponentLibrary('win', sources)
 
 if env.Bit('linux'):
   env.ComponentLibrary('linux', sources)
 
 if env.Bit('linux'):
   cpu_test = nacl_env.ComponentProgram('my_test', ['testing/test.c'],
       EXTRA_LIBS=['cpu_features','platform'])
 
   node = nacl_env.CommandTest(
       'cpu_x86_test.out',
       [cpu_test])
   nacl_env.AddNodeToTestSuite(node, ['small_tests'], 'run_cpu_x86_test')