43233/55794.

mysql-test/r/change_user.result:
  Don't use -1 integer wrap around. It used to work, but now we do what's
  actually in the documentation. In tests, we now use DEFAULT or the
  numeral equivalent (as we do in the 5.6 tests).
mysql-test/r/key_cache.result:
  Can't drop default key case is an error now, not a warning, for compatibility
  with 5.6.
mysql-test/r/variables.result:
  Can't drop default key case is an error now, not a warning, for compatibility
  with 5.6.
mysql-test/t/change_user.test:
  Don't use -1 integer wrap around. It used to work, but now we do what's
  actually in the documentation. In tests, we now use DEFAULT or the
  numeral equivalent (as we do in the 5.6 tests).
mysql-test/t/key_cache.test:
  Can't drop default key case is an error now, not a warning, for compatibility
  with 5.6.
mysql-test/t/variables.test:
  Can't drop default key case is an error now, not a warning, for compatibility
  with 5.6.
sql/mysqld.cc:
  0 is a legal (albeit magic) value: "drop key cache."
sql/set_var.cc:
  bound_unsigned() can go now, it was just a kludge until things are done
  The Right Way, which they are now.
  
  Can't drop default key case is an error now, not a warning, for compatibility
  with 5.6.
tests/mysql_client_test.c:
  Don't use -1 integer wrap around. It used to work, but now we do what's
  actually in the documentation. In tests, we now use DEFAULT or the
  numeral equivalent (as we do in the 5.6 tests).