auto merge of #15249 : aochagavia/rust/rand, r=huonw

Author: bors

src/librand/rand_impls.rs

@@ -203,6 +203,8 @@ tuple_impl!{A, B, C, D, E, F, G}
 tuple_impl!{A, B, C, D, E, F, G, H}
 tuple_impl!{A, B, C, D, E, F, G, H, I}
 tuple_impl!{A, B, C, D, E, F, G, H, I, J}
+tuple_impl!{A, B, C, D, E, F, G, H, I, J, K}
+tuple_impl!{A, B, C, D, E, F, G, H, I, J, K, L}
 
 impl<T:Rand> Rand for Option<T> {
     #[inline]