Make file system watcher compile on Mac OS 106, and add a runtime-call to test if the system suppor…

runtime/bin/file_system_watcher_android.cc

 // 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_ANDROID)
 
 #include "bin/file_system_watcher.h"
 
 #include <errno.h>  // NOLINT
 #include <sys/inotify.h>  // NOLINT
 
 
 namespace dart {
 namespace bin {
 
+bool FileSystemWatcher::IsSupported() {
+  return true;
+}
+
+
 intptr_t FileSystemWatcher::WatchPath(const char* path,
                                       int events,
                                       bool recursive) {
   int fd = TEMP_FAILURE_RETRY(inotify_init1(IN_NONBLOCK | IN_CLOEXEC));
   if (fd < 0) return -1;
   int list_events = 0;
   if (events & kCreate) list_events |= IN_CREATE;
   if (events & kModifyContent) list_events |= IN_MODIFY | IN_ATTRIB;
   if (events & kDelete) list_events |= IN_DELETE;
   if (events & kMove) list_events |= IN_MOVE;
@@ skipping 52 matching lines @@
   }
   ASSERT(offset == bytes);
   return events;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_ANDROID)