my_mkdir/my_rename/my_delete/my_fopen still misreport relative-path MAX_PATH overflow on Windows

Follow-up to MDEV-28746. my_win_sopen() was fixed to detect when a relative path (e.g. one built relative to the data directory after my_setwd()) resolves to a full path exceeding MAX_PATH, correctly reporting ENAMETOOLONG instead of a misleading ENOENT-derived error. The same gap may exists in my_mkdir (mysys/my_mkdir.c, affects CREATE DATABASE), my_rename (mysys/my_rename.c, affects RENAME/ALTER TABLE ... RENAME TO), my_delete (mysys/my_delete.c), and my_fopen (mysys/my_fopen.c) — they still do a bare my_osmaperr(GetLastError()) without the overlong path check, so the same root cause is still misreported for those operations.