fix crash when switching phonon backends on the fly, remember to stop libvlc media player before releasing it
fix crash when switching phonon backends on the fly, remember to stop libvlc media player before releasing it

Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

panzi/phonon-vlc,KDE/phonon-vlc,BinChengfei/phonon-vlc,panzi/phonon-vlc,BinChengfei/phonon-vlc,BinChengfei/phonon-vlc,KDE/phonon-vlc,KDE/phonon-vlc