Only send a quit signal for a second frontend.

    Unbeknownst to me kdeclarativefullscreenview is used for
    the messagecomposer contacts editor and some other fullscreenview's
    which should not result in quit signals on Windows CE.

    Now it is checked if the fullscreenview is really one of the 5
    Kontact Touch frontends before signaling the quit.

    BUG: 266525