macosx/framework: -[VLCMedia length] returns null every time after the first call.
macosx/framework: -[VLCMedia length] returns null every time after the first call.

Signed-off-by: Pierre d'Herbemont <845f4ee70830c827c363523bb1dc82128096c600@free.fr>

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