fsmonitor--daemon: on macOS support symlink

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 <zumix.cpp@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>