rust: lib: Rust 1.77 compat fixes

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

rust/alloc/slice.rs

@@ -59,6 +59,10 @@ pub use core::slice::{Chunks, Windows};
 pub use core::slice::{ChunksExact, ChunksExactMut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{ChunksMut, Split, SplitMut};
+#[cfg(version("1.77"))]
+#[stable(feature = "slice_chunk_by", since = "1.77.0")]
+pub use core::slice::{ChunkBy, ChunkByMut};
+#[cfg(not(version("1.77")))]
 #[unstable(feature = "slice_group_by", issue = "80552")]
 pub use core::slice::{GroupBy, GroupByMut};
 #[stable(feature = "rust1", since = "1.0.0")]