toolchain incorrect path

[AndreiCherniaev]

To avoid error like

CMake Warning at /home/user/Ubuntu_X11_Build_Qt_widgets/Qt_themself/build_artifacts_host_powerfull/lib/cmake/Qt6/qt.toolchain.cmake:56 (message):
The toolchain file to be chainloaded '../toolchain_host.cmake' does not exist.

Looks like instead of
-DCMAKE_TOOLCHAIN_FILE=../toolchain_host_powerfull.cmake
Should be
-DCMAKE_TOOLCHAIN_FILE="${MyQtBaseDir}/toolchain_host_powerfull.cmake"