iptables: update to 1.8.4

iptables: update to 1.8.4

Bump to iptable 1.8.4 and address packaging issue as mentioned in the
original bump/revert cycle.

"This reverts commit 10cbc896c0a26aecff37261450c21f29fb5b99db.
The updated iptables package does not build due to the following error
encountered on the buildbots:
    cp: cannot stat '.../iptables-1.8.4/ipkg-install/usr/lib/libiptc.so.*': No such file or directory

The changelog mentions "build: remove -Wl,--no-as-needed and libiptc.so" so
it appears as if further packaging changes are needed beyond a simple
version bump."

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>