Updated the reference in core::hint::spin_loop to the correct relative path.
Updated the reference in core::hint::spin_loop to the correct relative path.

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