[PATCH v2 0/3] MR651: comctl32: Check reference data pointer before using it.

[Zhiyi Zhang (＠zhiyi)]

Fix the crash when opening notepad++ v8.4.4 preference dialog before e52e42b.

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  v2: comctl32: Set reference data to zero on failure for GetWindowSubclass().
      comctl32: Check reference data pointer before using it.
      comctl32/tests: Add GetWindowSubclass() tests.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/651