Created placeholders for MallocHooks implementation and added define DART_USE_TCMALLOC to specifiy …

runtime/vm/vm_sources.gypi

 # Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # This file contains all sources (vm and tests) for the dart virtual machine.
 # Unit test files need to have a '_test' suffix appended to the name.
 {
   'sources': [
     'allocation.cc',
     'allocation.h',
@@ skipping 267 matching lines @@
     'locations.cc',
     'locations.h',
     'lockers.cc',
     'lockers.h',
     'log_test.cc',
     'log.cc',
     'log.h',
     'longjump.cc',
     'longjump.h',
     'longjump_test.cc',
+    'malloc_hooks.cc',
+    'malloc_hooks_unsupported.cc',
+    'malloc_hooks.h',
     'megamorphic_cache_table.cc',
     'megamorphic_cache_table.h',
     'memory_region.cc',
     'memory_region.h',
     'memory_region_test.cc',
     'message.cc',
     'message.h',
     'message_handler.cc',
     'message_handler.h',
     'message_handler_test.cc',
@@ skipping 248 matching lines @@
     'visitor.h',
     'weak_code.cc',
     'weak_code.h',
     'weak_table.cc',
     'weak_table.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
   ],
 }