QmlCppDebugger: Set cpp breakpoints right on startup (again)

Previous commit allows to hit cpp breakpoints before the QML engine
is up and running, so there is no need anymore to set breakpoints early
on.

Change-Id: Ia0de490d54057d51c4585c56fa9083de982ba97b
Reviewed-on: http://codereview.qt-project.org/5896


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Christiaan Janssen <christiaan.janssen@nokia.com>