gtphub: fix numerous segfaults, and other stupidities.

Initialize llist_heads to empty (2 were missing). Move those for struct gtphub
instances to gtphub_zero() (one moved, one added).

In from_[gs]gsns_read_cb(), use a return type that can actually reflect
negative return values.

resolved_addr.buf: no need to take the address of a byte array var
(cosmetic).

Pass the proper user data address to sgsn_ares_query(), not the address of
the pointer holding the user data address.

Initialize ggsn_lookup->expiry_entry (was missing). Publish the function for that
in gtphub.h so gtphub_ext.c can use it.

Sponsored-by: On-Waves ehi
diff --git a/openbsc/src/gprs/gtphub_ext.c b/openbsc/src/gprs/gtphub_ext.c
index 0d66273..98a9a40 100644
--- a/openbsc/src/gprs/gtphub_ext.c
+++ b/openbsc/src/gprs/gtphub_ext.c
@@ -94,7 +94,7 @@
 		goto remove_from_queue;
 	}
 
-	memcpy(&resolved_addr.buf, addr0, hostent->h_length);
+	memcpy(resolved_addr.buf, addr0, hostent->h_length);
 	resolved_addr.len = hostent->h_length;
 
 	LOGP(DGTPHUB, LOGL_NOTICE, "resolved addr %s\n",
@@ -122,7 +122,7 @@
 {
 	LOGP(DGTPHUB, LOGL_DEBUG, "Going to query %s (%p / %p)\n", lookup->apn_oi_str, lookup, &lookup->expiry_entry);
 
-	int rc = sgsn_ares_query(sgsn, lookup->apn_oi_str, ggsn_lookup_cb, &lookup);
+	int rc = sgsn_ares_query(sgsn, lookup->apn_oi_str, ggsn_lookup_cb, lookup);
 	if (rc != 0)
 		LOGP(DGTPHUB, LOGL_ERROR, "Failed to start ares query.\n");
 	return rc;
@@ -155,6 +155,7 @@
 	LOGP(DGTPHUB, LOGL_NOTICE, "Request to resolve IMSI '%s' with APN-NI '%s' (%p / %p)\n",
 	     imsi_str, apn_ni_str, lookup, &lookup->expiry_entry);
 
+	expiring_item_init(&lookup->expiry_entry);
 	lookup->hub = hub;
 
 	strncpy(lookup->imsi_str, imsi_str, sizeof(lookup->imsi_str));