Rebase slice_group_by stabilization PR

Author: dtolnay

compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch

@@ -21,7 +21,7 @@ index 897a5e9..331f66f 100644
 -#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
  #![cfg_attr(test, feature(cfg_match))]
  #![feature(int_roundings)]
- #![feature(slice_group_by)]
+ #![feature(split_array)]
 diff --git a/atomic.rs b/atomic.rs
 index b735957..ea728b6 100644
 --- a/atomic.rs

compiler/rustc_passes/src/dead.rs

@@ -917,7 +917,7 @@ impl<'tcx> DeadVisitor<'tcx> {
             return;
         }
         dead_codes.sort_by_key(|v| v.level);
-        for group in dead_codes[..].group_by(|a, b| a.level == b.level) {
+        for group in dead_codes[..].chunk_by(|a, b| a.level == b.level) {
             self.lint_at_single_level(&group, participle, Some(def_id), report_on);
         }
     }

compiler/rustc_passes/src/lib.rs

@@ -11,7 +11,6 @@
 #![feature(let_chains)]
 #![feature(map_try_insert)]
 #![feature(min_specialization)]
-#![feature(slice_group_by)]
 #![feature(try_blocks)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]