fsmonitor--daemon: on macOS support symlink

Resolves a problem where symbolic links were not showing up in diff when
created or modified.

kFSEventStreamEventFlagItemIsSymlink is also treated as a file update.
This is because kFSEventStreamEventFlagItemIsFile is not included in
FSEvents when creating or deleting symbolic links. For example:

$ ln -snf t test
  fsevent: '/path/to/dir/test', flags=0x40100 ItemCreated|ItemIsSymlink|
$ ln -snf ci test
  fsevent: '/path/to/dir/test', flags=0x40200 ItemIsSymlink|ItemRemoved|
  fsevent: '/path/to/dir/test', flags=0x40100 ItemCreated|ItemIsSymlink|

Signed-off-by: srz_zumix <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>

Author: srz-zumix

compat/fsmonitor/fsm-listen-darwin.c

@@ -336,7 +336,7 @@ static void fsevent_callback(ConstFSEventStreamRef streamRef,
 			 * know how much to invalidate/refresh.
 			 */
 
-			if (event_flags[k] & kFSEventStreamEventFlagItemIsFile) {
+			if (event_flags[k] & (kFSEventStreamEventFlagItemIsFile | kFSEventStreamEventFlagItemIsSymlink)) {
 				const char *rel = path_k +
 					state->path_worktree_watch.len + 1;