macosx: do not (mis)use the content view as the video view in fullscreen
macosx: do not (mis)use the content view as the video view in fullscreen

The content view can never be nil, so methods like removeFromSuperView
which are used do not work as expected. Thus, it was possible that the
content view is a dangling pointer, causing crashes when trying to draw
the window.

jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,krichter722/vlc,xkfz007/vlc,shyamalschandra/vlc,krichter722/vlc,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,vlc-mirror/vlc,xkfz007/vlc,krichter722/vlc,shyamalschandra/vlc,shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,vlc-mirror/vlc,vlc-mirror/vlc,xkfz007/vlc,xkfz007/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,vlc-mirror/vlc,xkfz007/vlc,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,vlc-mirror/vlc