Add unit test for 64-bit assembler

test/cctest/SConscript

 # Copyright 2008 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 46 matching lines @@
     'test-threads.cc',
     'test-utils.cc',
     'test-version.cc'
   ],
   'arch:arm':  ['test-assembler-arm.cc', 'test-disasm-arm.cc'],
   'arch:ia32': [
     'test-assembler-ia32.cc',
     'test-disasm-ia32.cc',
     'test-log-ia32.cc'
   ],
+  'arch:x64': ['test-assembler-x64.cc'],
   'os:linux':  ['test-platform-linux.cc'],
   'os:macos':  ['test-platform-macos.cc'],
   'os:nullos': ['test-platform-nullos.cc'],
   'os:win32':  ['test-platform-win32.cc']
 }
 
 
 def Build():
   cctest_files = context.GetRelevantSources(SOURCES)
   env = Environment()
   env.Replace(**context.flags['cctest'])
   context.ApplyEnvOverrides(env)
   # There seems to be a glitch in the way scons decides where to put
   # PDB files when compiling using MSVC so we specify it manually.
   # This should not affect any other platforms.
   return env.Program('cctest', ['cctest.cc', cctest_files, object_files],
       PDB='cctest.exe.pdb')
 
 
 program = Build()
 Return('program')