Set max character buffer len to 512 per MS specification

The MS specs determine that the character buffer lenngths
for usernames, domains, passwords, alternate shells, etc
can be up to 512 characters including the mandatory null
terminator.

neutrinordp/xrdp-neutrinordp.h

@@ -24,6 +24,7 @@
 #include "defines.h"
 #include "xrdp_rail.h"
 #include "xrdp_client_info.h"
+#include "xrdp_constants.h"
 
 /* this is the freerdp main header */
 #include <freerdp/freerdp.h>
@@ -196,9 +197,9 @@ struct mod
     int vmaj;
     int vmin;
     int vrev;
-    char username[256];
-    char password[256];
-    char domain[256];
+    char username[INFO_CLIENT_MAX_CB_LEN];
+    char password[INFO_CLIENT_MAX_CB_LEN];
+    char domain[INFO_CLIENT_MAX_CB_LEN];
     int bool_keyBoardSynced ; /* Numlock can be out of sync, we hold state here to resolve */
     int keyBoardLockInfo ; /* Holds initial numlock capslock state */