iptables: make it Multi-Arch: foreign

This change triggers a lintian warning which I don't know
how to handle by now, given libiptc is a *private* library
and should not be used by any package.

E: iptables: shlib-in-multi-arch-foreign-package lib/libiptc.so.0.0.0
N:
N:    The package is marked as Multi-Arch: foreign, but it includes a shared
N:    library in a public library directory.
N:
N:    Refer to https://wiki.ubuntu.com/MultiarchSpec

 for details.
N:
N:    Severity: serious, Certainty: certain
N:
N:    Check: shared-libs, Type: binary, udeb
N:

Closes: #776041
Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>

debian/control

@@ -22,6 +22,7 @@ Vcs-Git: https://alioth.debian.org/anonscm/git/pkg-netfilter/pkg-netfilter.git
 Vcs-Browser: https://alioth.debian.org/plugins/scmgit/cgi-bin/gitweb.cgi?p=pkg-netfilter/pkg-netfilter.git
 
 Package: iptables
+Multi-Arch: foreign
 Architecture: linux-any
 Depends: libxtables11 (=${binary:Version}), ${misc:Depends}, ${shlibs:Depends}
 Description: administration tools for packet filtering and NAT