Don't log anything if npkts == 0.

This occurs at RX DMA start, even though the RX FIFO has plenty of
space. I'll go figure out why, but this shouldn't cause people to
be spammed by these messages.
Don't let hastd use C11 atomics.

Due to possible concerns about the stability of C11 atomics, use our
existing atomics API instead.

Requested by:	pjd
Make libsupc++'s __cxa_call_terminate() prototype consistent with the
definition.

Submitted by:	dt71@gmx.com
MFC after:	3 days