Prefer to use qualified type names in generated code.

Emit type names like ir::Foo instead of just Foo to avoid very long
manual use declarations in files including generated code.

lib/cretonne/src/isa/riscv/enc_tables.rs

@@ -1,6 +1,5 @@
 //! Encoding tables for RISC-V.
 
-use ir::condcodes::IntCC;
 use ir;
 use isa;
 use isa::constraints::*;