Remove unused TyCtxt from remove_dead_blocks

This context was only needed by code for processing coverage statements, which
has been removed.

compiler/rustc_mir_transform/src/unreachable_prop.rs

@@ -65,7 +65,7 @@ impl MirPass<'_> for UnreachablePropagation {
         }
 
         if replaced {
-            simplify::remove_dead_blocks(tcx, body);
+            simplify::remove_dead_blocks(body);
         }
     }
 }