Fix more linkage errors (#2011)
diff --git a/include/fmt/os.h b/include/fmt/os.h
index 8815100..d44ea0c 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -388,7 +388,7 @@
     clear();
   }
 
-  void grow(size_t) final;
+  FMT_API void grow(size_t) override final;
 
   ostream(cstring_view path, const detail::ostream_params& params)
       : file_(path, params.oflag) {