magnify: correctly set i_visible_width/i_visible_height after dimension scaling
magnify: correctly set i_visible_width/i_visible_height after dimension scaling

Fix #10744

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