openssl: typo in comment

lib/vtls/openssl.c

@@ -733,7 +733,7 @@ static char *SSL_strerror(unsigned long error, char *buf, size_t size)
 {
 #ifdef HAVE_ERR_ERROR_STRING_N
   /* OpenSSL 0.9.6 and later has a function named
-     ERRO_error_string_n() that takes the size of the buffer as a
+     ERR_error_string_n() that takes the size of the buffer as a
      third argument */
   ERR_error_string_n(error, buf, size);
 #else