Debugger: Allow users to disable warning about unsupported breakpoints

QErrorMessage has by default a 'don't show the message again' checkbox.

Change-Id: I4bbb2172298db848870ed1abf9f7d6195bdfe49d
Reviewed-on: http://codereview.qt.nokia.com/400


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>