skins2: update current input if its associated item changes.
skins2: update current input if its associated item changes.

This is the right place to make sure an art file that was not available at
input launch time gets a chance to be displayed as soon as it becomes available.

vlc-mirror/vlc,xkfz007/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,shyamalschandra/vlc,vlc-mirror/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,xkfz007/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,krichter722/vlc,vlc-mirror/vlc-2.1,shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,xkfz007/vlc,shyamalschandra/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.1,krichter722/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,krichter722/vlc