...as it is not needed. Just provide the compilation arguments as part
of the Document.
As a side effect, re-initializing the backend after a crash is cheaper
and will not freeze the UI anymore (referenced bug).
Task-number: QTCREATORBUG-21097
Change-Id: I866e25ef1fd5e4d318df16612a7564469e6baa11
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>