Bump Rust and add skeleton code for irgen.

src/asmgen/mod.rs

@@ -10,6 +10,6 @@ impl Translate<ir::TranslationUnit> for Asmgen {
     type Error = ();
 
     fn translate(&mut self, _source: &ir::TranslationUnit) -> Result<Self::Target, Self::Error> {
-        todo!("homework 7")
+        todo!("Homework: Assembly Generation")
     }
 }