Tracking issue for lccc_lang_items

[chorman0773]

This is an lccc internal feature, used by libcore and liballoc.

Contents of feature

• core::ops::DerefMove -> Moving/Unwrapping Deref, implemented by Box, and stable_on_implicit_call
• core::ops::DerefPlace -> Creates a place from a mutable reference. Used for moving-deref and placement assignment.

Plans for stabilization:

Note: Refer to existing DerefMove RFC (TODO).

After successful use in lcrust, it is recommended that the features, or equivalents, be proposed to the rust T-libs and T-lang for merging into the rust language, and subsequent stablization.