KEncodingProber: Delete copy constructor and assignment operator
If someone was using them, it'd crash since it was raw-copying the d pointer
so you would end up with a double delete.
This is SIC, but IMHO it's fine, whoever gets a compiler failure has a bug to fix
Reviewed By: vkrause
Subscribers: apol, vkrause, kde-frameworks-devel
Differential Revision: https://phabricator.kde.org/D18134