Add RawRc type

Author: EFanZh

library/alloc/src/raw_rc/mod.rs

@@ -65,6 +65,7 @@ use core::cell::UnsafeCell;
 use core::mem;
 use core::sync::atomic::Atomic;
 
+mod raw_rc;
 mod raw_weak;
 mod rc_alloc;
 mod rc_layout;