Use the correct null constants for Mach threads, tasks, and hosts

util/mac/process_reader.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 60 matching lines @@
 namespace crashpad {
 
 ProcessReader::Thread::Thread()
     : thread_context(),
       float_context(),
       debug_context(),
       id(0),
       stack_region_address(0),
       stack_region_size(0),
       thread_specific_data_address(0),
-      port(MACH_PORT_NULL),
+      port(THREAD_NULL),
       suspend_count(0),
       priority(0) {
 }
 
 ProcessReader::Module::Module() : name(), reader(NULL), timestamp(0) {
 }
 
 ProcessReader::Module::~Module() {
 }
 
 ProcessReader::ProcessReader()
     : kern_proc_info_(),
       threads_(),
       modules_(),
       module_readers_(),
       task_memory_(),
-      task_(MACH_PORT_NULL),
+      task_(TASK_NULL),
       initialized_(),
       is_64_bit_(false),
       initialized_threads_(false),
       initialized_modules_(false) {
 }
 
 ProcessReader::~ProcessReader() {
   for (const Thread& thread : threads_) {
     kern_return_t kr = mach_port_deallocate(mach_task_self(), thread.port);
     MACH_LOG_IF(ERROR, kr != KERN_SUCCESS, kr) << "mach_port_deallocate";
@@ skipping 598 matching lines @@
       // The red zone would go lower into another region in memory, but no
       // region was found. Memory can only be captured to an address as low as
       // the base address of the region already found.
       *start_address = *region_base;
     }
   }
 #endif
 }
 
 }  // namespace crashpad