live555: change MIRROR for older versions

http://download.videolan.org/pub/videolan/testing/contrib/live555/ has dropped
everything before live.2011.12.23.tar.gz, change to using
http://ftp.freebsd.org/pub/FreeBSD/ports/distfiles/

 as it still has
live.2011.03.14.tar.gz.

Signed-off-by: Paul Barker <paul@paulbarker.me.uk>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>