Vendor import of tcpdump 4.4.0.
MFV: tcpdump 4.4.0.

MFC after:	4 weeks
- Checking for spurious interrupts is only necessary when using INTx.
  Actually, this may be further optimized for controller variants
  supporting one-shot MSIs but I'm lacking the necessary hardware for
  testing.
- Add some missing synchronization of the statistics and status DMA
  maps.

MFC after:	1 week