result.

For built-in functions like sqrt() function names are hard-coded and can be
compared by pointer. But this isn't the case for a used-defined stored
functions - names there are dynamical and should be compared as strings.

Now the Item_func::eq() function employs my_strcasecmp() function to compare
used-defined stored functions names.


mysql-test/t/sp.test:
  Added a test case for bug#25373: Stored functions wasn't compared correctly which leads to a wrong result.
mysql-test/r/sp.result:
  Added a test case for bug#25373: Stored functions wasn't compared correctly which leads to a wrong result.
sql/item_func.cc:
  Bug#25373: Stored functions wasn't compared correctly which leads to a wrong
  result.
  Now the Item_func::eq() function employs my_strcasecmp() function to compare
  used-defined stored functions names.