requested as they will be liquidated anyway when the root is
destroyed.

- Check if we really set the debug register.
- Added unaligned access exception check.
- Added single step exception check.

- implemented IOCTL_SERIAL_WAIT_ON_MASK for DeviceIoControl
  on serial lines in ntdll
- now using thread pool (instead of simple thread) for the
  background operations (this should help some high load
  situations)
- used this to implement WaitCommEvent on top NtDll functions
- in kernel32, removed now the no longer used termios/ioctls...
  for comm devices

has been asked for, and sets all the others to zero (with conformance
test).