Add stubs in platform_macos and file_system_watcher_macos for building the same

runtime/bin/platform_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.
 
 #include "platform/globals.h"
-#if defined(TARGET_OS_MACOS)
+#if defined(TARGET_OS_MACOS) || defined(TARGET_OS_IOS)

[Ivan Posva, 2015/06/09 21:20:03]

Please note that TARGET_OS_IOS also automatically means that TARGET_OS_MACOS is
defined. I am fine either way here, even if it is a bit redundant.

 
 #include <mach-o/dyld.h>
 
 #include "bin/file.h"
 #include "bin/platform.h"
 
+#if !defined(TARGET_OS_IOS)
 #include <crt_externs.h>  // NOLINT
+#endif
 #include <signal.h>  // NOLINT
 #include <string.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "bin/fdutils.h"
 
 
 namespace dart {
 namespace bin {
 
@@ skipping 26 matching lines @@
   return "dylib";
 }
 
 
 bool Platform::LocalHostname(char *buffer, intptr_t buffer_length) {
   return gethostname(buffer, buffer_length) == 0;
 }
 
 
 char** Platform::Environment(intptr_t* count) {
+#if defined(TARGET_OS_IOS)
+  return NULL;

[Ivan Posva, 2015/06/09 21:20:03]

Is there really no way to access environment variables on iOS?

+#else
   // Using environ directly is only safe as long as we do not
   // provide access to modifying environment variables.
   // On MacOS you have to do a bit of magic to get to the
   // environment strings.
   char** environ = *(_NSGetEnviron());
   intptr_t i = 0;
   char** tmp = environ;
   while (*(tmp++) != NULL) i++;
   *count = i;
   char** result = new char*[i];
   for (intptr_t current = 0; current < i; current++) {
     result[current] = environ[current];
   }
   return result;
+#endif
 }
 
 
 void Platform::FreeEnvironment(char** env, intptr_t count) {
   delete[] env;
 }
 
 
 char* Platform::ResolveExecutablePath() {
   // Get the required length of the buffer.
@@ skipping 11 matching lines @@
   // Return the canonical path as the returned path might contain symlinks.
   char* canon_path = File::GetCanonicalPath(path);
   free(path);
   return canon_path;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)