add osmo_sockaddr_to_str_buf/osmo_sockaddr_to_str

Add helper to format osmo_sockaddr into a string.

Change-Id: I917f25ebd1239eae5855d973ced15b93731e33a0
diff --git a/tests/socket/socket_test.ok b/tests/socket/socket_test.ok
index 9a52d44..236c011 100644
--- a/tests/socket/socket_test.ok
+++ b/tests/socket/socket_test.ok
@@ -21,3 +21,13 @@
 Checking osmo_sock_init_osa() must fail on mixed IPv4 & IPv6
 Checking osmo_sock_init_osa() must fail on mixed IPv6 & IPv4
 Checking osmo_sock_init_osa() must fail on invalid osmo_sockaddr
+Checking osmo_sockaddr_to_str_buf to small IPv4
+Checking osmo_sockaddr_to_str_buf IPv4
+Checking osmo_sockaddr_to_str_buf IPv6
+Checking osmo_sockaddr_to_str_buf too short IPv6
+Checking osmo_sockaddr_to_str_buf too short IPv6
+Checking osmo_sockaddr_to_str_buf only 5 bytes IPv6
+Checking osmo_sockaddr_to_str_buf only 5 bytes IPv6
+Checking osmo_sockaddr_to_str_buf long IPv6
+Checking osmo_sockaddr_to_str_buf long IPv6 port
+Checking osmo_sockaddr_to_str_buf long IPv6 port static buffer