searchview: fix uninitialized var on bogus `o='

searchview: fix uninitialized var on bogus `o='

When somebody enters an out-of-bounds `o=' (offset) query parameter
for a query which otherwise returns some results, we should avoid
triggering uninitialized variable warnings since we were unable
to extract min/max relevance percentages.  So just make up some
{min,max}_pct numbers for now if somebody tries that.

Aside from causing noise in stderr (often syslog), these were
otherwise harmless warning.  AFAIK, this could only be triggered
by someone entering URL parameters manually to view HTML, and
not in any generated URLs.