CPack/WiX: Add the build directory to IncludeSearchPaths for wix.exe In commit f2134169f6 (WiX: Add the build directory to IncludeSearchPaths for candle.exe, 2018-07-06, v3.13.0-rc1~318^2) we implemented this for WiX v3 with `candle.exe`. Use the same mechanism for Wix v4 and upwards for `wix.exe`.