ms: Use the new API to pass credentials to the event server

We are using the "autobind" feature of Linux to get a special
socket address. This allows us to have roughly 2^20 clients on
the system.

Change-Id: Ie9b9ac6267f40345baf7dbb3becaecf264a5df5f
diff --git a/src/osmo_ms_driver/lua/ms_support.lua b/src/osmo_ms_driver/lua/ms_support.lua
index 817a564..6490bec 100644
--- a/src/osmo_ms_driver/lua/ms_support.lua
+++ b/src/osmo_ms_driver/lua/ms_support.lua
@@ -11,6 +11,7 @@
 function mod.register(ms, path)
 	g_ms = ms
 
+	osmo.unix_passcred(g_c:getfd())
 	g_c:connect(path)
 
 	local event = {}