sql/event.cc:
  - make this not unsigned. gcc complains
sql/event_timed.cc:
  acl_getroot_no_password() is not there in libmysqld, disable it's usage
  in this case.
sql/set_var.cc:
  fix for the broken build of Serg. gcc seems to be pretty happy without
  the return and returns the value of the last statement