LP#1732591: (follow-up) fix major regressions

LP#1732591: (follow-up) fix major regressions

This patch works around two regressions introduced by a previous patch:

- record links from titles on the OPAC results page simply re-ran
  the search
- record links from cover images on the OPAC results page dropped
  all paramters

In one case, a 'record_url' should have been a mkurl() expression. In the
other case, the prior patch did not handle the clear_params parameter
correctly; an empty array is /not/ equivalent to undef, and all CGI parameters
were getting cleared.

This patch is offered in lieu of simply pushing a revert.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>