Docker: switch builds to g++-8 by default
Docker: switch builds to g++-8 by default

trikset/trikRuntime,trikset/trikRuntime,iakov/trikRuntime,iakov/trikRuntime,iakov/trikRuntime,iakov/trikRuntime,trikset/trikRuntime,trikset/trikRuntime,iakov/trikRuntime,trikset/trikRuntime