Avoid core dump if isql second or third argument is omitted.


diff -Naur mysql-connector-odbc-5.1.5r1144.orig/util/stringutil.c mysql-connector-odbc-5.1.5r1144/util/stringutil.c
--- mysql-connector-odbc-5.1.5r1144.orig/util/stringutil.c	2008-04-14 21:03:35.000000000 -0400
+++ mysql-connector-odbc-5.1.5r1144/util/stringutil.c	2009-02-16 14:28:59.000000000 -0500
@@ -52,7 +52,7 @@
   SQLINTEGER i, out_bytes;
   my_bool free_str= FALSE;
 
-  if (*len == SQL_NTS)
+  if (str && *len == SQL_NTS)
     *len= strlen((char *)str);
 
   if (!str || *len == 0)