Fix bug where a REHASH would cause us to loose track of remote RPC's (RRPC).

Like REHASHing while a module.list is in progress.

This due to missing SavePersistentPointer() in MOD_UNLOAD

src/modules/rpc/rpc.c

@@ -225,6 +225,8 @@ void free_config(void)
 MOD_UNLOAD()
 {
 	free_config();
+	SavePersistentPointer(modinfo, rrpc_list);
+	SavePersistentPointer(modinfo, outstanding_rrpc_list);
 	return MOD_SUCCESS;
 }