libcommon: socket: extend make_sock() prototype

This patch extends the make_sock() prototype so you can fully set
the fields priv_nr and data of the bsc_fd structure.

This is the first step to get rid of the internal make_sock()
implementation that ipaccess-proxy uses.

This patch includes a minor cleanup to pass INADDR_ANY instead
of zero, if you do not want to bind the socket to one specific
address.
diff --git a/openbsc/src/libgb/gprs_ns.c b/openbsc/src/libgb/gprs_ns.c
index 877a065..95e5a55 100644
--- a/openbsc/src/libgb/gprs_ns.c
+++ b/openbsc/src/libgb/gprs_ns.c
@@ -946,7 +946,7 @@
 	int ret;
 
 	ret = make_sock(&nsi->nsip.fd, IPPROTO_UDP, nsi->nsip.local_ip,
-			nsi->nsip.local_port, nsip_fd_cb);
+			nsi->nsip.local_port, 0, nsip_fd_cb, NULL);
 	if (ret < 0)
 		return ret;