The get_time_value function is added. It is used to obtain TIME values both
from items the can return time as an integer and from items that can return
time only as a string.
The Arg_comparator::compare_datetime function now uses pointer to a getter
function to obtain values to compare. Now this function is also used for
comparison of TIME values.
The get_value_func variable is added to the Arg_comparator class.
It points to a getter function for the DATE/DATETIME/TIME comparator.


mysql-test/t/type_time.test:
  Extended test case for the bug#29555.
mysql-test/r/type_time.result:
  Extended test case for the bug#29555.
sql/item_cmpfunc.cc:
  Extended fix for the bug#29555.
  The get_time_value function is added. It is used to obtain TIME values both
  from items the can return time as an integer and from items that can return
  time only as a string.
  The Arg_comparator::compare_datetime function now uses pointer to a getter
  function to obtain values to compare. Now this function is also used for
  comparison of TIME values.
sql/item_cmpfunc.h:
  Extended fix for the bug#29555.
  The get_value_func variable is added to the Arg_comparator class.
  It points to a getter function for the DATE/DATETIME/TIME comparator.