- Pass "buffers[i]" to val_str() in udf_handler::fix_fields insteead of NULL.
 - Add testcase for UDF that will load and run the udf_example functions 
   if available


sql/item_func.cc:
  Instead of passing a NULL pointer into val_str, use the "buffers" array to provide a temp string buffer.
sql/udf_example.cc:
  Spelling error"on"->"one"
mysql-test/include/have_udf.inc:
  New BitKeeper file ``mysql-test/include/have_udf.inc''
mysql-test/r/have_udf.require:
  New BitKeeper file ``mysql-test/r/have_udf.require''
mysql-test/r/udf.result:
  New BitKeeper file ``mysql-test/r/udf.result''
mysql-test/t/udf.test:
  New BitKeeper file ``mysql-test/t/udf.test''