Revert `Vec::spare_capacity_mut` impl to prevent pointers invalidation
Revert `Vec::spare_capacity_mut` impl to prevent pointers invalidation

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