tcpdump 4.6.2

Version bump, optional use of a newer libpcap, culled unrecognised configure options and mandatory OpenSSL dependency to escape this:

```
# /usr/local/sbin/tcpdump --version

tcpdump version 4.6.1
libpcap version 1.5.3 - Apple version 47
OpenSSL 0.9.8za 5 Jun 2014
```