extensions: add more test cases for iptables-test.py

Instead of using iptables-save-formatted files in the tests/ dir,
lets use the iptables-test.py framework for all matches/targets.

This obsoletes tests/ completely, will be removed in followup patch.

Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
diff --git a/extensions/libxt_socket.t b/extensions/libxt_socket.t
new file mode 100644
index 0000000..8c0036e
--- /dev/null
+++ b/extensions/libxt_socket.t
@@ -0,0 +1,4 @@
+:PREROUTING,INPUT
+*mangle
+-m socket;=;OK
+-m socket --transparent --nowildcard;=;OK