fix(core,kernel): replace #![feature(const_slice_from_raw_parts{ → _mut})]

`from_raw_parts` has been partially stabilized by
[rust-lang/rust#97522][1]. `from_raw_parts_mut` has been split into a
separate feature `const_slice_from_raw_parts_mut`.

[1]: rust-lang/rust#97522

Author: yvt

src/r3_core/src/lib.rs

@@ -3,12 +3,12 @@
 #![feature(const_nonnull_slice_from_raw_parts)]
 #![feature(const_maybe_uninit_uninit_array)]
 #![feature(const_maybe_uninit_assume_init)]
+#![feature(const_slice_from_raw_parts_mut)]
 #![feature(maybe_uninit_array_assume_init)]
 #![feature(const_maybe_uninit_as_mut_ptr)]
 #![feature(nonnull_slice_from_raw_parts)]
 #![feature(arbitrary_enum_discriminant)]
 #![feature(type_changing_struct_update)]
-#![feature(const_slice_from_raw_parts)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(const_precise_live_drops)]
 #![feature(const_raw_ptr_comparison)]

src/r3_kernel/src/lib.rs

@@ -1,8 +1,8 @@
 #![feature(const_maybe_uninit_array_assume_init)]
 #![feature(const_maybe_uninit_uninit_array)]
 #![feature(const_maybe_uninit_assume_init)]
+#![feature(const_slice_from_raw_parts_mut)]
 #![feature(maybe_uninit_array_assume_init)]
-#![feature(const_slice_from_raw_parts)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(const_precise_live_drops)]
 #![feature(const_raw_ptr_comparison)]