Make ~fn non-copyable, make &fn copyable, split barefn/closure types,

correct handling of moves for struct-record update.

Part of #3678.  Fixes #2828, #3904, #4719.

src/libstd/net_ip.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 //! Types/fns concerning Internet Protocol (IP), versions 4 & 6
-#[forbid(deprecated_mode)];
 
 use core::libc;
 use core::prelude::*;