So now it worked - but not with the version 10.3 of Xcode which I have reloaded but with my old version on another computer from last year.
Thereby I noticed something. When you start XCode for the first time, extensions are still loaded.
On my new system XCode 10.3 had afterwards 9,4 GB
On my old system XCode 10.3 has but 12.8 GB
and with this version HICE could be compiled.
I have now copied this version to my new computer
and made a new test - and E voilá everything there.
Thanks for your help.