don't build extra tools if build.tools is explicitly an empty list
don't build extra tools if build.tools is explicitly an empty list

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