Build rustdoc for run-make tests, not just run-make-fulldeps
Build rustdoc for run-make tests, not just run-make-fulldeps

Rustdoc almost never needs a full stage 2 compiler, and requiring
rustdoc tests to be in run-make-fulldeps adds a lot of compile time for
no reason.

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