live555: fix fetch problem

live.2013.04.30.tar.gz is no longer available at original live555 url
and the url of the FreeBSD mirror has changed according to[1].

[1] <http://ftp.freebsd.org/pub/FreeBSD/ports/distfiles/README.txt

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Signed-off-by: Steffen Sledz <sledz@dresearch-fe.de>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>