Silence error callback during from BDB during environment open

Silence error callback during from BDB during environment open
- EACCES from actually opening the environment is returned only
  through dbenv->open() return code, but annoyingly the EACCESS
  from trying to create a missing environment is "leaked" to the
  errcall, causing pesky "permission denied" errors for regular users
  if the environment doesn't (yet) exist. Enable errcall in time
  for dbenv->failchk() though to get all the details if something
  goes wrong there.