Add std::ptr::eq, for referential equality of &T references.
Add std::ptr::eq, for referential equality of &T references.

Fixes https://github.com/rust-lang/rfcs/issues/1155

graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust