Add fanotify support

**Description**
For security consideration in GR3, sometimes we may want to monitor and intercept filesystem events. fanotify-related system call is for this in Linux. So I think we should implement the fanotify_init and fanotify_mark system call.

ref:
-->http://man7.org/linux/man-pages/man7/fanotify.7.html

**Is this feature related to a specific bug?**

No

**Do you have a specific solution in mind?**
gVisor now has some inotify support. Look what linux does, I think we can abstract a fsnotify interface and implements inotify and fanotify under this interface.

Thanks,
Li Qiang