field.cc:
  Adding longlong range checking to return
  LONGLONG_MIN or LONGLONG_MAX when out of range. 
  Using (longlong) cast only when range is ok.
cast.test:
  Adding test case.
cast.result:
  Fixing results accordingly.


sql/field.cc:
  Bug#15098 CAST(column double TO signed int), wrong result
  Adding longlong range checking.
mysql-test/t/cast.test:
  Bug#15098 CAST(column double TO signed int), wrong result
  Adding longlong range checking.
mysql-test/r/cast.result:
  Fixing results accordingly.