- _WIN32_WINNT had wrong value to do workaround on Vista+ RegGetValueW.
- Do #undef and #define _WIN32_WINNT _WIN32_WINNT_VISTA in assoc.c.
- Delete _WIN32_WINNT hack in CMakeLists.txt.
CORE-9283
This Wine sync (that was not done against WineStaging) erased code
that had been submitted to WineStaging by the ReactOS team (clist.c
fixes, see r73565 a05881c and r73976 7b6b597) or added in r68042 9a78054.
To that aim I add explicit #if(n)def __REACTOS__ guards around the code.
