CRM-1930 crm_search_count does not do group search correctly

A group search will ignore an additional search parameter, returning only the number of members of the group:

Ex.: suppose group #1 contains 100 members, that contact_id = 63 is a member of 1, and that contact_id = 963 is not a member.

Then,
for $params = array(array('group' => array('1' => 1)), 'contact_id' => 63), crm_search_count($params) should return 1, and
for $params = array(array('group' => array('1' => 1)), 'contact_id' => 963), crm_search_count($params) should return 0.

In 1.7/r9284, it appears that crm_search_contact is returning 100 in both cases.