Rewrite function save_err_ptr_str() to not use sprintf() sprintf() is marked by MSVC as unsafe and suppressing compile warning does not work. It is still generated on AppVeyor. So rewrite code for converting pointer number to string via open coded for-loop and do not use unsafe sprintf() function anymore. New code correctly handles both 32bit and 64bit variants and does not use any #ifdef _MSC_VER anymore.