Add minimal testing of socket.c helper functions

Change-Id: I2773b3859a206f96fb8fa095d50a653d9eeb8d79
diff --git a/.gitignore b/.gitignore
index fb159c3..ad8354e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -98,6 +98,7 @@
 tests/fsm/fsm_test
 tests/write_queue/wqueue_test
 tests/oap/oap_test
+tests/socket/socket_test
 
 utils/osmo-arfcn
 utils/osmo-auc-gen