Optimise vec![false; N] to zero-alloc
Optimise vec![false; N] to zero-alloc

Nowadays booleans have a well-defined representation, so there is no reason not to optimise their allocation.

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