iptables/: Add a build system

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
iptables/: #include <xtables.h> instead of <iptables.h>

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
iptables/src/libxt_zone.c: Silence a warning

To silence a warning, include <ctype.h> for isspace().

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Merge pull request #1 from algernon/f/iptables-autotools

autotoolification of iptables/