rand_chacha: remove another line of dead code

Author: dhardy

rand_chacha/src/guts.rs

@@ -11,8 +11,6 @@
 
 use ppv_lite86::{dispatch, dispatch_light128};
 
-#[cfg(feature = "rustcrypto_api")] pub use stream_cipher::generic_array;
-
 pub use ppv_lite86::Machine;
 use ppv_lite86::{vec128_storage, ArithOps, BitOps32, LaneWords4, MultiLane, StoreBytes, Vec4};