Fix test for Windows

Author: bjorn3

tests/run-make/symbols-all-mangled/rmake.rs

@@ -26,6 +26,10 @@ fn symbols_check_archive(path: &str) {
             continue; // Correctly mangled
         }
 
+        if name.starts_with(".refptr.") {
+            continue; // COFF stub symbol
+        }
+
         let member_name =
             std::str::from_utf8(file.member(symbol.offset()).unwrap().name()).unwrap();
         if !member_name.ends_with(".rcgu.o") || member_name.contains("compiler_builtins") {