tray.c: Avoid -Waddress with MinGW

tray.c:783:36: error: the comparison will always
evaluate as ‘true’ for the pointer operand [...]
must not be NULL [-Werror=address]

True.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>

tray.c

@@ -780,7 +780,7 @@ SetMenuStatus(connection_t *c, conn_state_t state)
         config_group_t *parent = &o.groups[0];
         int pos = c->pos;
 
-        if (USE_NESTED_CONFIG_MENU && CONFIG_GROUP(c))
+        if (USE_NESTED_CONFIG_MENU)
         {
             parent = CONFIG_GROUP(c);
         }