Add test utility udp_proxy

Currently just forwards: will delay, duplicate and drop later.
diff --git a/programs/Makefile b/programs/Makefile
index 9238ae8..b3d8dbf 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -41,6 +41,7 @@
 	random/gen_random_ctr_drbg				\
 	test/ssl_cert_test	test/benchmark		\
 	test/selftest		test/ssl_test		\
+	test/udp_proxy							\
 	util/pem2der		util/strerror		\
 	x509/cert_app		x509/crl_app		\
 	x509/cert_req
@@ -217,6 +218,10 @@
 	echo   "  CC    test/ssl_test.c"
 	$(CC) $(CFLAGS) $(OFLAGS) test/ssl_test.c    $(LDFLAGS) -o $@
 
+test/udp_proxy: test/udp_proxy.c ../library/libpolarssl.a
+	echo   "  CC    test/udp_proxy.c"
+	$(CC) $(CFLAGS) $(OFLAGS) test/udp_proxy.c    $(LDFLAGS) -o $@
+
 test/o_p_test: test/o_p_test.c ../library/libpolarssl.a
 	echo   "  CC    test/o_p_test.c"
 	$(CC) $(CFLAGS) $(OFLAGS) test/o_p_test.c    $(LDFLAGS) -o $@ -lssl -lcrypto