Add basic C++ implementation of CPU profiler.

src/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 33 matching lines @@
     builtins.cc
     checks.cc
     circular-queue.cc
     code-stubs.cc
     codegen.cc
     compilation-cache.cc
     compiler.cc
     contexts.cc
     conversions.cc
     counters.cc
+    cpu-profiler.cc
     data-flow.cc
     dateparser.cc
     debug-agent.cc
     debug.cc
     disassembler.cc
     diy_fp.cc
     execution.cc
     factory.cc
     flags.cc
     frame-element.cc
@@ skipping 245 matching lines @@
       snapshot_cc = Command('snapshot.cc', [], [])
     snapshot_obj = context.ConfigureObject(env, snapshot_cc, CPPPATH=['.'])
   else:
     snapshot_obj = empty_snapshot_obj
   library_objs = [non_snapshot_files, libraries_obj, snapshot_obj]
   return (library_objs, d8_objs, [mksnapshot])
 
 
 (library_objs, d8_objs, mksnapshot) = ConfigureObjectFiles()
 Return('library_objs d8_objs mksnapshot')