Add Valgrind to CI

* Also pass `$*` to `configure` when invoking `ci-build.sh`, so one can
  e.g. run `./ci-build.sh --without-xscreensaver`

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

tests/unittests/test_cmd_disconnect.c

@@ -23,7 +23,7 @@ clears_chat_sessions(void** state)
     chat_session_recipient_active("mike@server.org", "work", FALSE);
 
     will_return(connection_get_status, JABBER_CONNECTED);
-    will_return(connection_get_barejid, strdup("myjid@myserver.com"));
+    will_return(connection_get_barejid, "myjid@myserver.com");
     expect_any_cons_show();
 
     gboolean result = cmd_disconnect(NULL, CMD_DISCONNECT, NULL);