[PATCH 0/1] MR3755: win32u: Correct the packed size of WM_GETDLGCODE when lparam is NULL.

[Tim Clem (＠tclem)]

If lparam is null, the current code crashes when it hits the memcpy in pack_user_message.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/3755