Auto merge of #859 - mwanner:freebsd-drop-drv, r=alexcrichton

Use IFF_OACTIVE and IFF_RUNNING even on FreeBSD. Deprecate the DRV ones.

According to @asomers, libc should propagate the use of the portable constants `IFF_OACTIVE` and `IFF_RUNNING` for user-space applications, instead of `IFF_DRV_OACTIVE` and `IFF_DRV_RUNNING`. It least that's my understanding of [his comment](https://github.com/nix-rust/nix/pull/667#discussion_r152396984) in nix-rust/nix#667.

src/unix/bsd/freebsdlike/freebsd/mod.rs

@@ -432,11 +432,17 @@ pub const IFF_DEBUG: ::c_int = 0x4; // (n) turn on debugging
 pub const IFF_LOOPBACK: ::c_int = 0x8; // (i) is a loopback net
 pub const IFF_POINTOPOINT: ::c_int = 0x10; // (i) is a point-to-point link
 // 0x20           was IFF_SMART
-pub const IFF_DRV_RUNNING: ::c_int = 0x40; // (d) resources allocated
+pub const IFF_RUNNING: ::c_int = 0x40; // (d) resources allocated
+#[deprecated(since="0.2.34",
+             note="please use the portable `IFF_RUNNING` constant instead")]
+pub const IFF_DRV_RUNNING: ::c_int = 0x40;
 pub const IFF_NOARP: ::c_int = 0x80; // (n) no address resolution protocol
 pub const IFF_PROMISC: ::c_int = 0x100; // (n) receive all packets
 pub const IFF_ALLMULTI: ::c_int = 0x200; // (n) receive all multicast packets
-pub const IFF_DRV_OACTIVE: ::c_int = 0x400; // (d) tx hardware queue is full
+pub const IFF_OACTIVE: ::c_int = 0x400; // (d) tx hardware queue is full
+#[deprecated(since="0.2.34",
+             note="please use the portable `IFF_OACTIVE` constant instead")]
+pub const IFF_DRV_OACTIVE: ::c_int = 0x400;
 pub const IFF_SIMPLEX: ::c_int = 0x800; // (i) can't hear own transmissions
 pub const IFF_LINK0: ::c_int = 0x1000; // per link layer defined bit
 pub const IFF_LINK1: ::c_int = 0x2000; // per link layer defined bit