Fix name of josn-c pkg-config file

Over 2 years ago json-c renamed its pc file from json.pc -> json-c.pc.

Signed-off-by: Justin Lecher <jlec@gentoo.org>
Merge pull request #105 from jlec/master

Fix name of json-c pkg-config file
Fix call to pcap_dispatch

This fix allows using zmap with libpcap 1.5.1, the semantic difference
of values 0 and -1 of this parameter is not entirely clear:

    "(In older versions of libpcap, the behavior when cnt was 0 was
    undefined; different platforms and devices behaved differently, so
    code that must work with older versions of libpcap should use -1,
    not 0, as the value of cnt.)"

http://www.tcpdump.org/manpages/pcap_loop.3pcap.html

Just using -1 worked for me.
Zero-out memory in xmalloc because safety.
Make die() static
Fix JSON support for OS X
adding CMake instructions to support building .deb packages
Respect install prefix better

Add -DRESPECT_INSTALL_PREFIX_CONFIG to have files in /etc also respect
the install prefix
macports: Add Portfile for zmap

The +redis variant is broken because there is no hiredis port.
The +json variant is broken because the json-c port does not update
the pkg-config database correctly.

Regular zmap works fine. I may fix the broken variants in the future
if motivated.
Homebrew Formula