Update InterfaceFlags

Add Flags: `IFF_NO_PI`, `IFF_TUN`, `IFF_TAP`.

CHANGELOG.md

@@ -10,6 +10,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 - Display and Debug for SysControlAddr now includes all fields.
   ([#837](https://github.com/nix-rust/nix/pull/837))
+- `nix::net::if_::InterfaceFlags` now support `IFF_NO_PI/IFF_TUN/IFF_TAP` flags on linux-like system.
+  ([#853](https://github.com/nix-rust/nix/pull/853))
 
 ### Fixed
 - Properly exposed 460800 and 921600 baud rates on NetBSD

src/net/if_.rs

@@ -215,6 +215,15 @@ libc_bitflags!(
         /// Don't exchange routing info.
         #[cfg(any(target_os = "solaris"))]
         IFF_NORTEXCH;
+        /// Do not provide packet information
+        #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))]
+        IFF_NO_PI as libc::c_int;
+        /// TUN device (no Ethernet headers) 
+        #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))]
+        IFF_TUN as libc::c_int;
+        /// TAP device
+        #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))]
+        IFF_TAP as libc::c_int;
         /// IPv4 interface.
         #[cfg(any(target_os = "solaris"))]
         IFF_IPV4;