Add --sout-bridge-in-placeholder-switch-on-iframe
Add --sout-bridge-in-placeholder-switch-on-iframe

Add default enabled option to force placeholder state toggling to
happen only on iframes. This removes artifacts at the expense of a
longer switch delay.

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