macosx: Clear logs once window is closed
macosx: Clear logs once window is closed

Logs are not recorded in background, so do not retain old logs
to avoid confusion.

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc