net/slirp: Improve file open error message This error reports failure to create a temporary file, and error_setg_file_open() would probably be too terse, so merely switch to error_setg_errno() to add errno information. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-ID: <20251121121438.1249498-12-armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>