Really remove io support when dart:io is unsupported.

runtime/bin/process_macos.cc

 // Copyright (c) 2012, 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.
 
+#if !defined(DART_IO_DISABLED)
+
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/process.h"
 
 #if !TARGET_OS_IOS
 #include <crt_externs.h>  // NOLINT
 #endif
 #include <errno.h>  // NOLINT
 #include <fcntl.h>  // NOLINT
 #include <poll.h>  // NOLINT
 #include <signal.h>  // NOLINT
 #include <stdio.h>  // NOLINT
 #include <stdlib.h>  // NOLINT
 #include <string.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "bin/dartutils.h"
 #include "bin/fdutils.h"
 #include "bin/lockers.h"
 #include "bin/log.h"
 #include "bin/thread.h"
 
 #include "platform/signal_blocker.h"
 #include "platform/utils.h"
 
 namespace dart {
 namespace bin {
 
+int Process::global_exit_code_ = 0;
+Mutex* Process::global_exit_code_mutex_ = new Mutex();
+
 // ProcessInfo is used to map a process id to the file descriptor for
 // the pipe used to communicate the exit code of the process to Dart.
 // ProcessInfo objects are kept in the static singly-linked
 // ProcessInfoList.
 class ProcessInfo {
  public:
   ProcessInfo(pid_t pid, intptr_t fd) : pid_(pid), fd_(fd) { }
   ~ProcessInfo() {
     int closed = TEMP_FAILURE_RETRY(close(fd_));
     if (closed != 0) {
@@ skipping 1053 matching lines @@
     bzero(&act, sizeof(act));
     act.sa_handler = SIG_DFL;
     VOID_NO_RETRY_EXPECTED(sigaction(signal, &act, NULL));
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)
+
+#endif  // !defined(DART_IO_DISABLED)