typeck/expr.rs: extract out check_expr_unary.
typeck/expr.rs: extract out check_expr_unary.

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