Update iOS FileSystemWatcher::WatchPath signature

runtime/bin/file_system_watcher_macos.cc

Index: runtime/bin/file_system_watcher_macos.cc
diff --git a/runtime/bin/file_system_watcher_macos.cc b/runtime/bin/file_system_watcher_macos.cc
index 1e0fa07870f60f15d479616f7cf6c74897863f2a..9a4f87a26cbe79dae3a6b6f9fec644544886ef93 100644
--- a/runtime/bin/file_system_watcher_macos.cc
+++ b/runtime/bin/file_system_watcher_macos.cc
@@ -416,6 +416,7 @@ intptr_t FileSystemWatcher::Init() {
 void FileSystemWatcher::Close(intptr_t id) {}
 
 intptr_t FileSystemWatcher::WatchPath(intptr_t id,
+                                      Namespace* namespc,
                                       const char* path,
                                       int events,
                                       bool recursive) {