Hi dtech,
thank you very much for the support and sorry for my late reply.
Yesterday i was able to try it again. It was exactly the problem where you did send me the information about.
If somebody else is having the same troubles, this is the fix for it:
Just install additional gcc + g++ and switch to to it. I used version 9.
Unfortunately now i am having a new problem. My box is booting with the image.
it is preparing the storage partition and rebooting fine again but then it stops at the Libreelec splash screen and not booting into Kodi.
Kodi is als not completely installed on the storage partition so i don't get any logs. If i put your original tar file into the update folder,
it is installing your system and after the reboot Kodi is starting up like it should.
How can i fix this trouble?