mysql-test/r/func_time.result:
  Fix for bug #16546: DATETIME+0 not always coerced the same way
    - test case
mysql-test/t/func_time.test:
  Fix for bug #16546: DATETIME+0 not always coerced the same way
    - test case
sql/item_timefunc.cc:
  Fix for bug #16546: DATETIME+0 not always coerced the same way
    - set decimals to DATETIME_DEC
sql/item_timefunc.h:
  Fix for bug #16546: DATETIME+0 not always coerced the same way
    - set decimals to DATETIME_DEC