inotify: Add AsFd to allow using with epoll (issue #1998)

Author: VorpalBlade

src/sys/inotify.rs

@@ -32,7 +32,7 @@ use libc::{c_char, c_int};
 use std::ffi::{CStr, OsStr, OsString};
 use std::mem::{size_of, MaybeUninit};
 use std::os::unix::ffi::OsStrExt;
-use std::os::unix::io::{AsRawFd, FromRawFd, OwnedFd, RawFd};
+use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, OwnedFd, RawFd};
 use std::ptr;
 
 libc_bitflags! {
@@ -240,3 +240,9 @@ impl FromRawFd for Inotify {
         Inotify { fd: OwnedFd::from_raw_fd(fd) }
     }
 }
+
+impl AsFd for Inotify {
+    fn as_fd(&'_ self) -> BorrowedFd<'_> {
+        self.fd.as_fd()
+    }
+}