Update link to pbzip2 website.

[ghuls]

Website for pbzip2 does not exist anymore, now seems to be hosted at:
http://compression.great-site.net/pbzip2/

Downloading pbzip2_1.1.13.orig.tar.gz
from https://launchpad.net/ubuntu/+source/pbzip2/1.1.13-1build1 and looking in AUTHORS lists the following website:
https://gilchrist.great-site.net/jeff/, which lists: http://compression.great-site.net/pbzip2/ , so I guess it is save to assume that this is owned by the original developer.

[marcelm]

Thanks!