Allow none Sized types in assert_eq!
Allow none Sized types in assert_eq!

format_args! doesn't support none Sized types so we should just pass it the references to left_val and right_val.

This fixes `assert_eq!([1, 2, 3][..], vec![1, 2, 3][..])` for example.

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