Try to depend only on the ir module being in scope.

Generated code should used qualified names assuming that `ir` is in
scope, not everything else.

lib/cretonne/src/legalizer/mod.rs

@@ -19,7 +19,6 @@ use ir::{self, Function, Cursor};
 use ir::condcodes::IntCC;
 use isa::TargetIsa;
 use bitset::BitSet;
-use ir::instructions::ValueTypeSet;
 
 mod boundary;
 mod split;