py: Add %q format support to mp_[v]printf, and use it.
diff --git a/py/builtinimport.c b/py/builtinimport.c
index d92cff6..5cab1d5 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -319,7 +319,7 @@
                         nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "module not found"));
                     } else {
                         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
-                            "no module named '%s'", qstr_str(mod_name)));
+                            "no module named '%q'", mod_name));
                     }
                 }
             } else {