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/libcore/rand.rs

@@ -10,10 +10,6 @@
 
 //! Random number generation
 
-// NB: transitional, de-mode-ing.
-#[forbid(deprecated_mode)];
-#[forbid(deprecated_pattern)];
-
 use int;
 use prelude::*;
 use str;