No longer accidentally attempting to parse NBSTAT RRs as SRV RRs.

The NetBios name service RFC (1002) specified NBSTAT (NetBios Status)
resource records to have identifier 0x0021.  The DNS SRV RFC specified
SRV records to have identifier 33.  Unfortunately those are the
same number. :)

We now check the resp port to handle this situation better so that
we won't be attempting to parse NBSTAT records as SRV (which
causes several weird messages).