build-sys: add bug reporting address and home page to configure

$ ./configure --help | tail -2
Report bugs to <openafs-bugs@openafs.org>.
OpenAFS home page: <http://www.openafs.org/>.

Change-Id: I862b7501f3c964eea800e1aad5f2fc0c551b9fb8
Reviewed-on: http://gerrit.openafs.org/10006
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>