[dsc] Allow multiple bpf_program and append content

[Jerry Lundström]

Hi Klaus,

On 01/23/17 10:02, Klaus Darilion wrote:
> BPF program is: (host 111.222.68.96 or ..........) and (udp port 53 or tcp port 53)
> Opening interface eth1
> Warning: Kernel filter failed: Cannot allocate memory
> Pcap_init: FD_SET 4
> Opening interface eth2
> Warning: Kernel filter failed: Cannot allocate memory
> Pcap_init: FD_SET 5

Thanks, I've added this to pcap-thread now and will update dsc develop
branch to generate a warning to syslog also.  That warning comes from
libpcap and outputs to stderr which is closed if dsc runs as daemon.

Cheers,
Jerry