Problem: we may get unexpected results comparing [u]longlong values as doubles.
Fix: adjust the test to use integer comparators.
Note: it's not a real fix, we have to implement some new comparators 
to completely solve the original problem (see my comment in the bug report).


mysql-test/r/func_in.result:
  Fix for bug #28748: "Select" returning one value too few
    - result adjusted.
mysql-test/t/func_in.test:
  Fix for bug #28748: "Select" returning one value too few
    - test adjusted to use integer comparisons.