Fix missed sign-compare warning

llvm-svn: 290473

libcxx/test/libcxx/localization/locales/locale.convenience/conversions/conversions.string/ctor_move.pass.cpp

@@ -27,7 +27,7 @@ int main()
     // interesting state.
     Myconv myconv;
     myconv.from_bytes("\xF1\x80\x80\x83");
-    const int old_converted = myconv.converted();
+    const auto old_converted = myconv.converted();
     assert(myconv.converted() == 4);
     // move construct a new converter and make sure the state is the same.
     Myconv myconv2(std::move(myconv));