Remove unused return values from resume and cleanup_ret

Given that these instructions are diverging, not every codegen backend
may be able to produce a return value for them.

Author: bjorn3

src/builder.rs

@@ -1275,15 +1275,15 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         // TODO(antoyo)
     }
 
-    fn resume(&mut self, _exn: RValue<'gcc>) -> RValue<'gcc> {
+    fn resume(&mut self, _exn: RValue<'gcc>) {
         unimplemented!();
     }
 
     fn cleanup_pad(&mut self, _parent: Option<RValue<'gcc>>, _args: &[RValue<'gcc>]) -> Funclet {
         unimplemented!();
     }
 
-    fn cleanup_ret(&mut self, _funclet: &Funclet, _unwind: Option<Block<'gcc>>) -> RValue<'gcc> {
+    fn cleanup_ret(&mut self, _funclet: &Funclet, _unwind: Option<Block<'gcc>>) {
         unimplemented!();
     }