libpcap: Update to 1.10.3

Local changes:

- In contrib/libpcap/pcap/bpf.h, do not include pcap/dlt.h. Our system
net/dlt.h is pulled in from net/bpf.h.
- sys/net/dlt.h: Incorporate changes from libpcap 1.10.3.
- lib/libpcap/Makefile: Update for libpcap 1.10.3.

Changelog: https://git.tcpdump.org/libpcap/blob/95691ebe7564afa3faa5c6ba0dbd17e351be455a:/CHANGES
Reviewed by: emaste
Obtained from: https://www.tcpdump.org/release/libpcap-1.10.3.tar.gz
Sponsored by: The FreeBSD Foundation

MFV r313676: libpcap 1.8.1

MFC after: 1 month

MFV r276759: libpcap 1.6.2.

MFC after: 1 month

Merge from vendor branch: update libpcap to 1.2.1.

MFC after: 2 weeks

Merge libpcap-1.1.1.

Merge libpcap 1.0.0.

Flatten vendor/libpcap and remove keyword expansion.

Import of libpcap v0.9.4

Virgin import of libpcap v0.9.1 (alpha 096) from tcpdump.org

Import libpcap 0.7.1, from
http://www.tcpdump.org/release/libpcap-0.7.1.tar.gz

Virgin import of tcpdump.org libpcap v0.6.2

Virgin import of tcpdump.org libpcap v0.5

Virgin import of LBL libpcap version 0.2.1.
Obtained from: ftp://ftp.ee.lbl.gov/libpcap.tar.Z on 19-Aug-1996.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

- Import the HEAD csup code which is the basis for the cvsmode work.

Import of libpcap v0.9.4

Virgin import of libpcap v0.9.1 (alpha 096) from tcpdump.org

Import libpcap 0.7.1, from
http://www.tcpdump.org/release/libpcap-0.7.1.tar.gz

Virgin import of tcpdump.org libpcap v0.6.2

Virgin import of tcpdump.org libpcap v0.5

Virgin import of LBL libpcap version 0.2.1.
Obtained from: ftp://ftp.ee.lbl.gov/libpcap.tar.Z on 19-Aug-1996.